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Game Mastering


Adventures and Campaigns

As the Game Master, you wear many hats: storyteller, entertainer, judge, inventor, and player. You’re in charge of creating an entire world for your friends to explore, and you fill the shoes of every nonplayer character they interact with. While this can be a lot of work, it can also be deeply rewarding. As the GM, you’re the ultimate arbiter of everything in your game—you can change setting details or even fundamental rules of the game as you see fit—but below are some systems and tips to help make your GMing experience fun and smooth.

Building an Adventure

How much work you put into preparing your adventure is up to you. The easiest approach is to simply modify or run a published adventure (see the sidebar). While published adventures are usually quite intricate, with beautiful maps and interwoven storylines, don’t let that intimidate you. If you’re the only one running your adventure, you can easily get by with just a few notes, such as an outline of the plot, a map or two of main adventure sites, and a few stat blocks or notes for the creatures you plan to use as enemies. Some people run entirely off the cuff, while others write everything down. Whatever lets you relax and have fun at the table is the right choice.

If you decide to write everything out, however, remember that an adventure is not a novel. The other players control the main characters, and you should leave room for them to shape the action. If the characters steal a shuttle and head down to the planet when you expected them to try and capture the ship’s bridge, don’t despair! Just grab the Starfinder Alien Archive, flip it open, and tell them what weird creatures—perhaps lurking within some strange alien ruins inscribed with mystical signs—they find when they land. Maybe you can still bring the story back around to your original idea after this side quest, but adapting your story in response to player action is what makes a group storytelling game exciting and surprising for the GM as well as the players!

The following section contains some key issues you should consider before sitting down to run a game, as well as elements that, if prepared in advance, can save you a lot of time and frustration at the table.

Stat Blocks

Stat blocks are one of the most complex parts of the game, but also the most useful. They tell you everything you need to know about a creature or character’s abilities in a fight, much like a condensed version of a character sheet.

How you use stat blocks is up to you. Some Game Masters like to create custom stat blocks for most of the allies and enemies encountered during an adventure, some like to create them only for the biggest and baddest enemy characters, and others are perfectly happy to repurpose statistics from other adventures or books like the Alien Archive. Some GMs don’t even bother with full stat blocks and just write down a few key statistics—Armor Classes, attacks and damage, Hit Points, and saving throws—and ignore the rest unless it becomes important.

All of these approaches are valid, but in general, the ways you expect your party to interact with a character determine what you need. If your PCs go to a nonplayer character (NPC) for research assistance before their next mission, then you probably need to know only a few skill values, whereas you’ll probably need to know all the combat statistics for the Free Captain pirate they battle in the adventure’s climax. Also remember that in addition to using published characters and creatures as written, you can simply “reskin” those creatures. If you use the statistics for a haan but describe fins and jets instead of claws and balloons, a cold spray instead of firespray, and a swim speed instead of a fly speed, congratulations—you’ve created a brand-new alien, and your players will never know the difference!

Level Equivalent for Monsters and NPCs

Many abilities and effects are based on a creature’s level. Unlike player characters, however, monsters and NPCs don’t have levels. Instead, the CR of a monster or NPC functions as its level for any ability or effect based on level.

Designing Encounters

An encounter is any event that presents the PCs with a specific problem that they must solve. Most encounters involve combat with monsters or hostile NPCs, but there are many other types: a corridor full of robotic traps, a fraught negotiation with government authorities, an environmental hazard on a strange planet, an encrypted database that needs to be hacked, or anything else that adds drama to the game. Some encounters involve puzzles, interpersonal interactions, physical feats, or other tasks that can be overcome entirely with roleplaying and skill checks, but the most common encounters are also the most complex to build—combat encounters.

When designing a combat encounter, decide what level of challenge you want your PCs to face and follow the steps below.

Step 1: Determine APL

The first thing you need to do is determine your players’ Average Party Level (APL), which represents how much of a challenge the group can handle. To get this number, add up the levels of all characters in the party, divide the sum by the number of party members, then round to the nearest whole number (this is an exception to the usual “round down” rule). If the group contains fewer than four characters, subtract 1 from the result; if the group contains six or more characters, add 1 to the total. For example, if a group has six characters, two at 4th level and four at 5th level, its APL is 6 (28 total levels divided by six characters equals 5 after rounding up, and 1 is added for having six characters).

Step 2: Determine CR

Challenge Rating (CR) is a convenient number used to indicate the relative danger presented by an enemy, trap, hazard, or other encounter; the higher the CR, the more dangerous the encounter. Refer to Table 11–1: Encounter Difficulty to determine the Challenge Rating your group should face depending on the Difficulty of the challenge you want and the group’s APL.

Step 3: Build the Encounter

Determine the total experience point (XP) award for the encounter by looking up its CR on Table 11–3: Experience Point Awards. This gives you an “XP budget” for the encounter. Every creature, trap, and hazard is worth an amount of XP determined by its CR, as noted on the table. To build your encounter, simply add creatures, traps, and hazards whose combined XP does not exceed the total XP budget for your encounter. It’s easiest to add the highest CR challenges first and then reach the total by including lesser challenges.

For example, let’s say you want your group of six 11th-level PCs (APL 12) to face a hard encounter against a crafty necrovite (CR 13) and some elephantine ellicoths (CR 9 each). Table 11–1: Encounter Difficulty indicates to you that a hard encounter for a group of APL 12 is equivalent to CR 14. According to Table 11–3: Experience Point Awards, a CR 14 encounter has an XP budget of 38,400 XP. At CR 13, the necrovite is worth 25,600 XP, leaving you with 12,800 XP to spend on ellicoths. Ellicoths are worth 6,400 XP apiece, so the encounter can support two ellicoths in its XP budget. or you could skip the necrovite and use three ellicoths instead, leaving you with 19,200 XP to spend on other creatures or hazards (perhaps a CR 12 creature that shares the ellicoths’ lair).

Special Considerations

Creating fun and balanced encounters is both an art and a science. Don’t be afraid to stray from the formulas by making changes—sometimes called ad hoc adjustments—that you think will make the encounter more fun or manageable for your particular party. In addition to the basic rules above, consider whether any of the following factors might apply to your encounter.

Adding NPCs

Creatures with abilities that match a class, such as creatures that belong to the PC races, function differently than creatures with substantial innate abilities. Their power comes more from gear than from nature, and they might have skills and abilities similar to those of PCs. Generally, the CR of an NPC equals the level of a PC with the same abilities—for example, an NPC with abilities similar to a 2nd-level technomancer would be CR 2. An NPC usually has armor and a weapon each with a level equal to its CR, give or take a level, and possibly one or two more items of a level equal to its CR. For more information on creating nonplayer characters, see the Alien Archive.

CR Equivalencies

The sheer number of experience points involved in building high-CR encounters can seem daunting, especially when you’re trying to craft an encounter on the fly. When using a large number of identical creatures, Table 11–2: CR Equivalencies can simplify the math by combining them into one CR, making it easier to find their total XP value. For example, using this table, you can see that four CR 8 creatures (worth 4,800 XP each) are equivalent to one CR 12 creature (worth 19,200 XP). You can also use this table to work backward and build encounters with much less math. Need a CR 7 encounter using CR 4 creatures? Just check the table, and you’ll see that you need three CR 4 creatures to create a CR 7 encounter.

Terrain Factors

An encounter against a creature that’s out of its favored element (like an enormous dragon encountered in a tiny cave) gives the PCs an advantage. In such a situation, you should probably build the encounter as normal—you don’t want to accidentally overcompensate and kill your party—but when you award experience for the encounter, you may want to do so as if the encounter were 1 CR lower than its actual CR.

The reverse is also true, but only to an extent. Creature CRs are assigned with the assumption that a given creature is encountered in its favored terrain. Encountering a water-breathing kalo in an underwater area shouldn’t increase the XP you award for that encounter, even if none of the PCs breathe water. But if the terrain impacts the encounter significantly, you can increase the XP award as if the encounter’s CR were 1 higher. For example, an encounter against a creature with blindsight in an area with no natural light needs no CR adjustment, but an encounter against the same creature where any light brought into it is suppressed might be considered +1 CR.

As a general rule, the goal of ad hoc XP adjustments based on factors like terrain is not to penalize PCs for doing well, but to make sure they’re being challenged and rewarded appropriately.

Gear Adjustments

You can significantly increase or decrease the power level of an NPC by adjusting its gear, particularly its weapons or crucial items such as powered armor. An NPC encountered with no gear should have its CR reduced by 1 (provided that the loss of gear actually hampers it). An NPC with better gear than normal—such as a weapon with 2 levels higher than the NPC’s CR or a large number of items with a level equal to its CR—has a CR of 1 higher than normal. This equipment impacts your treasure budget, so make overgeared NPCs like this with caution!

Tactical Considerations

Just as a player slowly learns how to use his character’s abilities, so does a GM learn how to best deploy her collection of foes. CR can’t cover every situation, so a GM should think through both a creature’s abilities and the encounter’s setting for any potential pitfalls.

One major concern is the CR of the enemy. The CR system works best when the CR of each of the GM’s creatures is relatively close to the PCs’ Average Party Level. It might be tempting to throw a single higher-CR creature against the party, and sometimes that works out fine, but you may run the risk of obliterating the party when their saving throws aren’t yet high enough to protect against the creature’s abilities. Conversely, if you throw a horde of CR 1 creatures against your party with an APL of 8, those creatures are unlikely to hit the characters’ Armor Classes or succeed with any of their abilities, and thus they won’t be challenging, no matter how many you include.

Yet just as a tidal wave of low-CR enemies can become a tensionless slog for players, fighting a single opponent can also be a bore, depending on that opponent’s abilities. A lone technomancer without any bodyguards or defenses in place might find himself quickly surrounded or unable to cast his spells after being grappled, and a creature with a single powerful attack might still not be a great match for a party of five slightly less powerful characters due to the sheer number of attacks they have each round. In general, the strongest encounters have a handful of enemies that guard vulnerable creatures with powerful abilities and balance out the PCs’ number of actions each round.

Gaining Experience

Characters advance in level by overcoming challenges ranging from combat situations to diplomatic encounters. All of these are symbolized by experience points (XP). Many GMs choose to simply keep a list of all the encounters PCs overcome during a session, add together the experience points, and award them in a lump sum at the end of the session. That way, if characters earn enough XP to gain levels, you won’t have to pause the game while they level up their characters, and you can instead let them do so between sessions.

Every opponent, trap, or obstacle the PCs overcome (including starship combat and vehicle chases) is worth a set amount of XP, as determined by CR. Purely roleplaying encounters are generally assumed to have a CR equal to the Average Party Level, but you may award XP as if it were higher or lower, depending on Difficulty. Note, however, that encounters with a CR of less than the APL – 10 merit no XP award, as they’re too easy. Similarly, using starship weapons against a settlement or driving an asteroid into a planet may kill thousands, but in such instances, the party should generally not receive XP or wealth, as these massacres are neither heroic nor challenging. Experience gained in a fight comes not from enemy death but from expertise acquired as a result of combat, which such impersonal situations lack.

To award XP, take your list of defeated encounters and find the value of each encounter’s CR under the “Total XP” column on Table 11–3: Experience Point Awards. Add up the total XP values for each CR and then divide this total by the number of characters. The result is the amount of XP each character earns. For a slightly less exact method, you can add up the individual XP awards listed in the table for a group of the appropriate size. In this case, the division between characters is done for you.

In addition, don’t be afraid to give players extra XP when they conclude a major storyline or accomplish something important. These “story awards” can consist of any amount of XP. While a good rule of thumb is to award twice the XP for a CR equal to the group’s APL, you can also customize your story award amounts to help your players’ characters reach a particular level for the next adventure you want to run.

Table 11–1: Encounter Difficulty
Difficulty CR Equivalency
Easy APL – 1
Average APL
Challenging APL + 1
Hard APL + 2
Epic APL + 3
Table 11–2: CR Equivalencies
Number of Creatures CR Equivalency
1 creature CR
2 creatures CR + 2
3 creatures CR + 3
4 creatures CR + 4
6 creatures CR + 5
8 creatures CR + 6
12 creatures CR + 7
16 creatures CR + 8
Table 11–3: Experience Point Awards
CR Total XP Individual XP (By No. of Players)
1–3 4–5 6+
1/8 50 15 15 10
1/6 65 20 15 10
1/4 100 35 25 15
1/3 135 45 35 25
1/2 200 65 50 35
1 400 135 100 65
2 600 200 150 100
3 800 265 200 135
4 1,200 400 300 200
5 1,600 535 400 265
6 2,400 800 600 400
7 3,200 1,070 800 535
8 4,800 1,600 1,200 800
9 6,400 2,130 1,600 1,070
10 9,600 3,200 2,400 1,600
11 12,800 4,270 3,200 2,130
12 19,200 6,400 4,800 3,200
13 25,600 8,530 6,400 4,270
14 38,400 12,800 9,600 6,400
15 51,200 17,100 12,800 8,530
16 76,800 25,600 19,200 12,800
17 102,400 34,100 25,600 17,100
18 153,600 51,200 38,400 25,600
19 204,800 68,300 51,200 34,100
20 307,200 102,000 76,800 51,200
21 409,600 137,000 102,400 68,300
22 614,400 205,000 153,600 102,400
23 819,200 273,000 204,800 137,000
24 1,228,800 410,000 307,200 204,800
25 1,638,400 546,000 409,600 273,000

Gaining Wealth

As PCs gain levels, they tend to obtain wealth. This game assumes that all PCs of equivalent level have roughly equal amounts of wealth in the form of gear, magic items, and raw currency. Since a PC’s primary way of gaining wealth is through adventuring, it’s important to Moderate the amount you place in your adventures. Thus, the amount of wealth PCs earn from their adventures is tied to the Challenge Rating of the encounters they face.

Wealth per Encounter

Table 11–4: Wealth Gains per Encounter lists the amount of treasure each encounter should award based on its CR. When looking at this number, it’s important to understand that it represents wealth from many different sources: hard currency, looted items, and earned or story-based wealth. Relying too much on any one category can skew the game’s power balance. Additionally, most encounters are part of an overarching adventure, in which case it’s useful to look at wealth for the adventure as a whole. Don’t be afraid to have some encounters grant more wealth while others grant less, as long as it balances out by the end of the adventure. (After all, a well-armed NPC is more likely to be carrying valuable items than a mindless beast.) Below are some important considerations regarding each type of wealth.

Table 11–4: Wealth Gains Per Encounter
CR Wealth Gain (In Credits)
1/3 150
1/2 230
1 460
2 775
3 1,100
4 1,400
5 3,100
6 3,900
7 4,600
8 5,400
9 10,000
10 14,700
11 25,000
12 34,000
13 50,000
14 77,000
15 113,000
16 178,000
17 260,000
18 405,000
19 555,000
20 782,000


Gear looted from fallen enemies or otherwise acquired during adventures can generally be sold for only 10% of its face value. This is important to gameplay, in that it discourages players from picking up every dropped helmet or low-level weapon and turning their ship into a flying garage sale, yet it’s also crucial to keep in mind when placing treasure. If an item is significantly better than the PCs’ current gear, assume they keep it and factor it in at its full value. If it’s no better than what they already have, assume they sell it when they have the chance. (Comparing the item level to the Average Party Level can be an excellent guideline for this purpose.) For example, if the characters face a high-CR enemy with a correspondingly awesome laser rifle, assume they keep it. If they fight eight aeon troopers with armor comparable to their own, assume most groups will leave it rather than carry eight bulky sets of armor with them. In general, beware of providing single items far above your party’s APL. Instead, provide several items equal to or only slightly better than your party’s current gear, and then make up the rest with consumable items and items likely to be resold.

Story-Based Wealth

Given the inefficiency of constantly looting and selling enemy gear, this game assumes at least part of player wealth comes from story-based sources, usually completing a mission or adventure. Perhaps it’s payment for finishing a patron’s quest, a gift from a grateful populace, a bounty on a criminal, or proceeds from selling an alien artifact or the exclusive interview rights to a PC’s account of an adventure. Regardless of the source, consider setting aside part of the budget from your encounters to allow for large lump-sum payments at appropriate points in the story.

Hard Currency

It’s important to include credits in your rewards, so that players can buy items appropriate to their characters, but avoid regularly giving out handfuls of credsticks, as pooling large sums of liquid capital can enable a party to buy better gear than would normally be appropriate for the group’s APL.

Table 11–5: Character Wealth By Level
PC Level Wealth (In Credits)
1st 1,000
2nd 2,000
3rd 4,000
4th 6,000
5th 9,000
6th 15,000
7th 23,000
8th 33,000
9th 45,000
10th 66,000
11th 100,000
12th 150,000
13th 225,000
14th 333,000
15th 500,000
16th 750,000
17th 1,125,000
18th 1,700,000
19th 2,550,000
20th 3,775,000

Wealth by Level

Table 11–5: Character Wealth by Level lists the amount of treasure each PC is expected to have at a specific level.

In addition to providing benchmarks to make sure existing characters remain balanced, it can also be used to budget gear for characters starting above 1st level, such as a new character created to replace a dead one. Characters in this latter case should spend no more than half their total wealth on any single item. For a balanced approach, PCs built after 1st level should spend no more than 25% of their wealth on weapons and 25% on armor and protective devices.


This is a roleplaying game of interplanetary travel and exploration, and it assumes that most adventures will start with PCs either already having or quickly gaining access to a starship. But starships are expensive—what’s to stop them from simply selling their starship and retiring, or using the money to buy gear far too powerful for their level?

The answer is you, the GM. Starships are not considered part of character wealth and thus are not intended to be sold (unless it’s part of a trade-in to obtain a different starship). How to frame this is up to you. Some GMs may prefer to simply tell the players not to sell the ship because it would ruin the game. If you need an in-character reason, however, there are many: The ship could be the equivalent of a company car from whatever patron or faction the PCs are working for. It could be a family heirloom they’re contractually not allowed to sell. It could be stolen and thus unsellable without getting the PCs arrested. It could have a hyperintelligent AI that’s bonded to its crew and doesn’t allow itself to be sold. Whatever the justification, the real answer is that starships are just too much fun to restrict to high-level play. (Though if you want to play an entire campaign on one planet or simply have PCs pay for passage when they need to get somewhere, that’s fine, too!)

Before the Game

Everyone approaches game mastering differently—some with intensive preparation, others with a sticky note and a prayer. Yet, regardless of your personal style, there are a few matters every GM should consider in advance to save time at the table.

If you’re running a published adventure, be sure to read it beforehand so that you know what you’re in for and can adequately prepare your notes and foreshadow upcoming events. (If short on time, you can sometimes read just the first few encounters —enough to keep several steps ahead of the players.) If you’re creating your own adventure, make sure you have enough written down to feel comfortable. Gather any props you need, such as miniatures and handouts, in addition to the usual dice, pencils, Tactical maps, and so forth. Consider helping your players prep for the game as well, such as by resolving character story issues that don’t involve the group as a whole (perhaps even via one-on-one side quests), answering questions, and helping them level up their characters.

It’s also important to consider real-world logistics. Make sure that all the players can make it to the game; if someone can’t, consider whether it’s still worth running the game, and if so, what happens to that person’s character. Do you or another player play him? Does he continue to gain wealth and experience, or will he fall behind the rest of the group? Also, consider matters such as food, children, pets, and other factors, and have a plan to handle any concerns that might arise.

Running the Game

Addressed below are several of the common situations and issues that you’ll invariably need to handle during the game.

Skill DCs

It is up to you, as the GM, to determine the DCs of the various skill checks the players will attempt during play. Many of the skill descriptions include guidance on typical DCs for skill checks, but there may be times when you need to come up with a DC on your own. If a skill check does not have a predetermined DC, or if a player wants to attempt a task that is not covered in a skill’s description, use the following guidelines. A challenging DC for a skill check is equal to 15 + 1-1/2 × the CR of the encounter or the PCs’ Average Party Level (APL). For an easier check, you might reduce the DC by 5, while increasing the DC by 5 makes for a more difficult check. Changing the DC by 10 or more makes for either a trivial check with little chance of failure or a prohibitively high check with little chance of success, so be cautious when adjusting skill check DCs!

Rolling and Fudging

Player cheating can ruin a game, but as a GM, you may sometimes find yourself in situations where cheating might actually improve the game. We prefer to call this “fudging” rather than cheating, and while you should try to avoid it when you can, you are the law in your game and shouldn’t feel bound by the dice. A GM should be impartial and fair, and in theory, that’s what random dice results help support. At the same time, you’re trying to create a compelling story, and if fudging a given roll makes a scene more fun and satisfying for the players in the end—go for it! It’s no good if a single random roll of the dice would result in a premature end to your campaign or in a character’s death when the player did everything right. However, be wary of using fudging to nullify players’ achievements. Remember that you’re playing with the group, not against it. Maybe you didn’t expect the players to take down your villain so quickly, but as long as they had fun, who cares?

Published Adventures

Published adventures are a busy Game Master’s best friend. Not only do they allow you to sit down and start playing quickly without coming up with intricate storylines or cool encounters in advance, but by studying how they’re put together, you can hone your own adventure-creating skills. A published adventure is the script that lets you, as the GM, Focus on the directing and acting portions of your job.

It’s important to remember, however, that the writer of a published adventure doesn’t know your group or their characters. If your players are all paranoid, then an adventure involving an unexpected betrayal by a friendly NPC may not work as well. Similarly, if one of your characters has a deep hatred for necromantic elebrians, her player may have more fun if you change the villain from a member of the Aspis Consortium to an agent of the Bone Sages. Customizing adventures to your group is an easy way to raise the stakes in your game and make things feel more personal.

If you’re interested in published adventures, Adventure Path products offer finely crafted adventures that are tied together into epic six-part campaigns. For more information, visit

An easy way to avoid getting called out on your fudging is to make your dice rolls behind a GM screen, so that players can’t see the results. But don’t worry overmuch about being “caught.” As the GM, your responsibility is to the experience, not the dice. But if you elect to roll your dice in the open, you still shouldn’t show a die roll that would give a player knowledge that their character wouldn’t have, such as a saving throw for a disease a character doesn’t know she’s been exposed to.

In addition to not being bound by die rolls, don’t feel tied to the predetermined plot of an encounter or the rules as written. Feel free to adjust the events or interpret the rules creatively, especially in cases where you as the GM made a poor assumption to begin with. For example, you might design an encounter where a pack of demons have invaded a space station through a planar rift, only to realize too late that none of the PCs have good-aligned weapons and thus deal very little damage. In this case, it’s okay to “cheat” and say these particular demons are hurt by normal weapons, or have a chaplain show up at the last moment to bless the PCs’ weapons. As long as you can keep such ad-hoc developments to a minimum, these on-the-spot adjustments can even enhance the game—perhaps a church now demands a favor from the PCs, sparking a new adventure!

GM Fiat

Debates over rules inevitably drag a game down and should be put to rest as quickly as possible. As the GM, you set the law of your game, and your interpretation of the rules is the one that matters most. When complications regarding rules interpretations occur, listen to the players involved and strive to be fair, but don’t feel like you need to convince them. If the rule in question isn’t one you’re familiar with, you can go with a player’s interpretation, perhaps with the caveat that you’ll read up on the rule after the game and make an official ruling going forward from the next session. Alternatively, you can simply rule that something works in a way that helps the story move on.

One handy tool to keep on hand is the GM fiat: simply give a player a +2 bonus or a –2 penalty to a die roll if no one at the table is precisely sure how a situation might be handled by the rules. For example, a character who attempts to trip a robot in a room where the floor is magnetized could take a –2 penalty to his attempt, at your discretion, since the magnetic pull exerted by the floor anchors the construct.

Player Character Death

Eventually, through bad luck or bad tactics, a player character is going to die, or else suffer some similarly permanent fate such as petrification or being shot into deep space at relativistic speeds. A player character’s death doesn’t need to be a terrible experience. In fact, going out in a blaze of glory can become a dramatic highlight for the player and the group as a whole!

When a character dies, try to resolve the current conflict or combat as quickly as possible. Once that’s handled, take the player aside for a moment and find out whether she’d prefer for the group to try to save her character or simply create a new one.

You aren’t required to let a dead character return to life. Sometimes dead is dead—and a horror-themed game often benefits from a sense of danger—but it’s nice to take a player’s feelings into account. If it’s possible for the party to get a character raised or reincarnated, don’t delay it with additional encounters; just gloss over the return to civilization so you can get the player back into the game as quickly as possible. If you’d rather treat the situation as the seed for a side quest, consider offering to let the PC play an established NPC for the rest of the session so she isn’t bored. A PC death is a great time to end the session, since you can then handle unresolved issues out of game and get the player back in the action by the start of the next session.

If the player of a dead character instead prefers to move on to a new character, consider the NPC option above to keep her entertained for the rest of the session, or let her create her new character there at the table. Once the player’s new character is done, let the other players take a 5-minute break while you step aside to talk to the player, learn about her new character, and work out a way to introduce the new party member quickly.

One other thing that PC death can do is bloat the surviving characters’ treasure. If a party simply splits up or sells a dead PC’s gear, the group can become obscenely overgeared for its level. Thus, it’s usually easier to simply assume that the dead PC’s personal gear (though not necessarily important story items belonging to the group) is destroyed, lost, or otherwise goes away.

Difficult Players

As with any group activity, sometimes you’ll run into a troublemaker. Don’t be shy about politely and firmly asking a player to alter his behavior if he’s being inappropriate, antagonistic, or otherwise annoying—and don’t accept “But I’m just acting how my character would!” as an excuse. If a player (or character) is negatively impacting the rest of the group’s experience and won’t change his behavior when asked, it’s your duty as the Game Master to tell him to leave.

Campaign Journal

Having a record of each session’s events can help you remember details and keep a sense of continuity. Consider taking notes during a game or getting a player who’s excited about such things to write up a campaign journal summarizing each adventure. These can also be distributed to remind players where you left off.

Ending the Campaign

The most important thing in a campaign is to end it at a point that’s satisfying for the story, such as when a major storyline wraps up or after a climactic battle with a longtime foe. After each significant adventure arc, discuss as a group whether you’d rather continue with these characters or start something entirely new. Some people like to play many short adventures with different characters, while others like to run the same campaign for years. There’s no wrong answer!


The universe is an endless expanse of adventuring potential. On its billions of worlds, physics create every possible permutation of geology, while life’s endless creativity gives rise to organisms both eerily familiar and defying imagination. Regardless of their design, all of these creatures struggle to survive and thrive in their native habitats, from icy seas and lush fungus jungles to the savage pyroclastic flows of tidally heated moons or the rusting hulks of ancient alien megastructures.

The following section contains rules to help you as GM adjudicate the game universe, including rules for the vastness of space, for various types of planets and the different terrains that may be found on them, and for environmental effects and hazards that may come into play in a variety of settings. Rules for settlements and structures both natural and artificial are presented at the end of the section.


The immeasurable gulf of space is home to everything on the Material Plane, housing more stars and planets than could ever be recorded. During their careers, the player characters will undoubtedly need to venture into space. Traveling from one planet to another, exiting the atmosphere of a planetoid, or visiting an orbiting space station are all examples of common travel that require at least a brief time in space. Many hazards of space can be mitigated by wearing armor or a standard space suit, but sometimes unlucky spacefaring adventurers get caught without them!

Cosmic Rays

“Cosmic rays” is a catchall term for various interStellar radiation effects. They use the same rules as radiation. Most habitable planets maintain atmospheres capable of repelling these emissions. Such protected planets allow, at most, a low amount of radiation in infrequent bursts. Planets devoid of a protective atmosphere are constantly assailed by radiation of medium to severe intensity.


The void of space is effectively empty of matter, and this vacuum is perhaps the greatest danger of outer space. A creature introduced to a vacuum immediately begins to suffocate (see Suffocation and Drowning) and takes 1d6 bludgeoning damage per round (no saving throw). Because a vacuum has no effective temperature, the void of outer space presents no dangers from cold temperatures. A creature retains its body heat for several hours in a vacuum. Sound doesn’t travel in a vacuum.

Decompression occurs when a creature suddenly transitions from a pressurized environment to a vacuum, such as by being flung out of an airlock or being inside a sealed structure that becomes heavily damaged. Such a creature takes 3d6 bludgeoning damage (no saving throw) in addition to any suffocation damage.

Most creatures travel the vacuum of space in a starship.

Astronomical Objects

Most living beings begin their lives on floating astronomical objects. These planets, planetoids, and stars are the hub of much adventure and vary in complexity of design and makeup. A brief summary of the different types of astronomical objects is presented below, along with various rules associated with each.

Classification of Astronomical Objects

There exist several different types of astronomical objects. Summarized below are the most prominent types encountered during interStellar exploration.


An asteroid is a fractured chunk of matter, notable for being too small to be considered a proper planetoid. Asteroids commonly lack any sort of ecosystem and are often bereft of an atmosphere and breathable air. Many see asteroids as exploitable resources, given that they are often rich in minerals of varying rarity.

Gas Giant

As their name suggests, gas giants are worlds composed entirely of gas—frequently elements such as hydrogen and helium. They lack any natural solid surfaces to walk on and so have no proper ground. Creatures unable to fly or without flight-capable equipment or magic tumble toward the dense core of the world at the falling speed of a standard-gravity planet. Such a fall often takes days, given the immense size of these worlds. Near the center of a gas giant, a creature is subject to extreme gravity. The heart of a gas giant acts in many ways like a star (see Star below), including destroying creatures that don’t have full immunity to fire.

Irregular World

Some planets exist outside of the typical description of a (mostly) spherical mass of gases or silicate rocks and metals. These irregular worlds come in a variety of shapes, many of which are still considered theoretical. Some worlds might be Artificially designed in the shape of a torus. Other worlds, like a planet in the form of a cube or a world that is entirely flat, exist as the result of cosmic abnormalities or the direct intervention of the divine.


Satellites are objects, such as moons, orbiting any other form of planetoid. “Satellite” is a classification that can be applied to other astronomical objects as well, as many asteroids and terrestrial worlds are also satellites. Unlike other types of astronomical objects, a satellite isn’t necessarily a natural object. Alien markers and space stations are but a few types of Artificial constructs that hang in the gravitational field of planets. Some planets have only a single moon, while others (such as gas giants) boast dozens of objects caught in their gravitational fields.


A star—sometimes multiple stars—typically rests at the heart of a planetary system. Stars are massive balls of incandescent plasma that blast their orbiting planetoids with heat. While there are various categorizations of stars, from blue dwarf stars to yellow hypergiants, all stars produce enough heat to pose similar hazards to most adventurers. The surface of a star is so hot that only full immunity to fire allows a creature to survive there. Any creatures or items not immune to fire are instantly and utterly consumed down to the molecular level—only spells such as miracle or wish can bring back such victims.

Solar Flares: Occasionally, stars let off bursts of intense energy, visible upon their surfaces as flares of roiling plasma. These disturbances have a deadly and immediate effect on things on or near the surfaces of such turbulent stars. The peripheral danger of these flares is the devastating effect they have on unshielded electronic equipment and radio communications. These distortions can be felt millions of miles away from the star, and typically they cause various electronics and radio communications to cease functioning for 6d6×10 minutes.


An atmosphere is a layer of gases held in place by the pull of a planetoid’s gravity. The gravity and temperature of a planetoid impact its ability to retain an atmosphere. Most planets and planetoids support some manner of atmosphere. In addition to hospitable atmospheres, there are various other types of atmosphere that serve as hazards to most life.


As the name suggests, a corrosive atmosphere eats away at matter. The type and speed of the erosion varies, but the most common use of this term describes atmospheres capable of dissolving most matter. A typical corrosive atmosphere deals anywhere from 1 acid damage per minute up to 10d6 acid damage per round to creatures and objects within. Certain metals and treated materials may be immune to the specific atmosphere of a planet, and often the corrosion can be mitigated with dutiful preparation.

No Atmosphere

A creature on a planet without an atmosphere (or with an atmosphere so thin that it is effectively airless) is exposed to a vacuum.


A normal atmosphere is one that can support the majority of breathing life-forms. Most such atmospheres are composed of some combination of oxygen, nitrogen, and other nontoxic gases.

Terrestrial World

Most people use the word “planet” to refer to a terrestrial world. The ones closest to the star of a Solar system are the worlds most likely to be naturally habitable. They’re home to varying ecosystems, from barren, rocky landscapes to vibrant jungles of lush plant life and rushing waterways. Such worlds are sometimes categorized by their predominant features, leading to titles such as desert world, ice world, jungle world, and lava world.


A nonacclimated creature operating in a thick atmosphere treats it as somewhat harmful, due to the extra chemical compounds in the air and the increased atmospheric pressure. Every hour, such a creature must succeed at a Fortitude save (DC = 15 + 1 per previous check) or become sickened. This condition ends when the creature returns to a normal atmosphere. Conversely, the increased weight of the air grants a +4 circumstance bonus to Acrobatics checks to fly or Piloting checks to keep an aircraft in flight.

Severely thick atmospheres are far more dangerous. Every minute, a creature in such an atmosphere must succeed at a Fortitude save (DC = 15 + 1 per previous check) or begin to suffocate (see Suffocation and Drowning) as its lungs cease coping with the density of the oxygen inhaled and lose the strength to keep pumping air into its bloodstream.


Thinner atmospheres tend to cause a nonacclimated creature to have Difficulty breathing and become extremely tired. A typical thin atmosphere requires such a creature to succeed at a Fortitude save each hour (DC = 15 +1 per previous check) or become fatigued. The fatigue ends when the creature returns to a normal atmosphere.

Severely thin atmospheres can cause long-term oxygen deprivation to those affected in addition to the effects of a standard thin atmosphere. The first time a creature in a severely thin atmosphere fails its Fortitude save, it must succeed at a DC 25 Fortitude save or take 1 damage to all ability scores. A creature acclimated to high altitude (see Hill and Mountain Terrain) gains a +4 insight bonus to its saving throw to resist this effect.


Toxic atmospheres are composed of poisonous compounds and vary radically in their consistencies. Some toxic atmospheres are capable of sustaining oxygen-breathing life-forms, while others immediately suffocate those within them. Regardless of whether or not they allow creatures to breathe, toxic atmospheres are threats to most living creatures, as they act as an inhaled poison. Though the specific type of poison varies, many toxic atmospheres act as existing poisons but with radically different onset times and save DCs. Low-level toxic atmospheres can have onset times measured in hours or days, while heavily toxic atmospheres have onset times measured in rounds.


The following section includes information on a variety of biomes found on planets. Some planets could be entirely made up of a single biome, such as desert or forest worlds, while other planets contain a mix of the following terrain types.

Aerial Terrain

On worlds where the atmosphere expands high above the physical boundaries of the surface, there exists a region of open air. Similarly, gas giants are made up of nothing more than a vast atmosphere, held in place by a starlike core. The most common rules sections to reference when using aerial terrain are Falling, Gravity, Suffocation and Drowning, and Weather. The rules for flying with the Acrobatics skill are also critical for many creatures operating in an aerial environment.


Most clouds are little more than condensed gas that obfuscates vision. Treat a cloud in an aerial environment using the same rules as fog cloud, except it’s a nonmagical effect. Other types of cloud exist, such as corrosive or toxic clouds, which operate in the same manner as those types of atmospheres (see above).

Stealth and Detection in Aerial Terrain

How far a character can see in the air depends on the presence or absence of clouds. Creatures can usually see 5d8×100 feet if the sky is completely clear, with minimal clouds (or other aerial objects) blocking their views. Clouds generally provide enough concealment to hide within (though the hiding creature might have Difficulty seeing out from its hiding place).

Aquatic Terrain

Aquatic terrain can be one of the least hospitable to PCs because most can’t breathe underwater. The ocean floor holds many marvels, including undersea analogues of any of the other terrain elements described in this section, but if characters find themselves in the water because they were bull-rushed off the back of a transport ship, the kelp beds or volcanic vents hundreds of feet below them don’t matter. The most common rules sections to reference when using aquatic terrain are Suffocation and Drowning and Underwater Combat. The rules for swimming with the Athletics skill are also critical for many creatures operating in an aquatic environment.

Deep Water

Lakes and oceans simply require a swim speed or successful Athletics checks to move through (typically, DC 10 in calm water, DC 15 in rough water, DC 20 in stormy water, and DC 30 in maelstrom water). Characters need a way to breathe if they’re underwater; lacking that, they risk drowning. When underwater, characters can move in any direction, including up and down.

Extreme Depths

At certain depths, the pressure of the surrounding water becomes so great that characters might be affected as if they were in a thick or severely thick atmosphere, even if they can breathe underwater.

Stealth and Detection Underwater

How far a character can see underwater depends on the water’s clarity. As a guideline, creatures can see 4d8×100 feet if the water is clear and 1d8×10 feet in murky water. Running water is always murky, unless it’s in a particularly large, slow-moving river. It is hard to find cover or concealment to hide underwater (except along the sea floor).

Desert Terrain

Desert terrain exists in cold, temperate, and warm climates, but all deserts share one common trait: very little precipitation. The three categories of desert terrain are tundra (cold desert), rocky deserts (often temperate), and sandy deserts (often warm). The most common rules sections to reference for adventures in these areas are Cold Dangers, Heat Dangers, Starvation and Thirst, and Weather.

Stealth and Detection in the Desert

In general, the maximum distance in desert terrain at which a creature can succeed at a Perception check to detect the presence of others is 6d6×20 feet; beyond this distance, elevation changes and heat distortion in warm deserts makes sight-based Perception checks impossible. The presence of dunes in sandy deserts limits spotting distance to 6d6×10 feet. The scarcity of undergrowth or other elements that offer concealment or cover makes using Stealth more difficult.

Forest Terrain

A forest can be composed of more than trees. On some worlds, vast fungal growths tower into the sky, while on others metallic veins rise from the ground and connect in spidery canopies. Common rules sections to reference for forests are Catching on Fire, Falling Objects, Smoke Effects, and Vision and Light.


Most forests are filled with trees, or something akin to trees, which provide partial cover to those standing in the same square as a tree. An average tree has an AC of 4, a hardness of 5, and 150 HP (see rules on smashing an object). A successful DC 15 Athletics check is enough to climb most trees.


Fungal blooms, vines, roots, and short bushes cover much of the ground in a forest. Undergrowth counts as difficult terrain, provides concealment (20% miss chance), and increases the DCs of Acrobatics and Stealth checks by 2. Squares with undergrowth are often clustered together. Undergrowth and trees aren’t mutually exclusive; it’s common for a 5-foot square to have both a tree and undergrowth.

Stealth and Detection in a Forest

In a sparse forest, the maximum distance at which a creature can succeed at a Perception check to detect the presence of others is 3d6×10 feet. In a medium forest, this distance is 2d8×10 feet, and in a dense forest it is 2d6×10 feet.

Because any square with undergrowth provides concealment, it’s usually easy for a creature to use the Stealth skill to hide. Logs and massive trees provide cover, which also makes hiding possible.

The background noise of a forest makes Perception checks that rely on sound more difficult, increasing the DC of the check by 2 (not 1) per 10 feet.

Hill and Mountain Terrain

Hill terrain describes rises in the immediate area, often multiple hills spread over miles. This type of terrain can occur in any other biome. Mountains are steeply rising rock, metal, or even the organic crust of the planet. The most common rules sections to reference when using hill and mountain terrain are Cold Dangers, Falling, and Weather.


Usually formed by natural geological processes, chasms are common dangers in mountainous areas. Chasms aren’t hidden, so characters won’t (usually) fall into them by accident. A typical chasm is 2d4×10 feet deep, at least 20 feet long, and anywhere from 5 to 20 feet wide. It usually requires a successful DC 15 Athletics check to climb the wall of a chasm. In mountain terrain, chasms are typically 2d8×10 feet deep.

Rock Wall

A vertical plane of stone, a rock wall requires one or more successful DC 25 Athletics checks to ascend. A typical rock wall is from 2d4×10 feet tall to 2d8×10 feet tall.

High Altitude

At particularly high altitudes, the thinning atmosphere poses a challenge for many creatures, with the same effects as a thin atmosphere. A creature residing at a high altitude for 1 month becomes acclimated and no longer takes these penalties, but it loses this benefit if it spends more than 2 months away from high-altitude terrain and must reacclimatize upon returning.

Stealth and Detection in Hills and Mountains

As a guideline, the maximum distance in mountain terrain at which a creature can succeed at a Perception check to detect the presence of others is 4d10×10 feet. In hill terrain, the maximum distance is 2d10×10 feet. It’s easier to hear distant sounds in the mountains. The DCs of Perception checks that rely on sound increase by 1 per 20 feet between listener and source, not 1 per 10 feet.

Marsh Terrain

Two categories of marsh exist: relatively dry moors and watery swamps. Both are often bordered by lakes, which are effectively a third category of terrain found in marshes. The most common rules sections to reference for marshes and swamps are Suffocation and Drowning, Underwater Combat, and Weather (see below).


If a square is part of a shallow bog, it has deep mud or standing water of about 1 foot in depth. It counts as difficult terrain, and the DCs of Acrobatics checks attempted in such a square increase by 2.

A square that is part of a deep bog has roughly 4 feet of standing water. It counts as difficult terrain, and Medium or larger creatures must spend 4 squares of movement to move into a square with a deep bog, or characters can swim if they wish. Small or smaller creatures must swim to move through a deep bog. Tumbling is impossible in a deep bog.

The water in a deep bog provides cover for Medium or larger creatures. Smaller creatures gain improved cover. Medium or larger creatures can crouch as a move action to gain this improved cover. A creature with this improved cover takes a –10 penalty to attacks against creatures that aren’t underwater.

Deep bog squares are usually clustered together and surrounded by an irregular ring of shallow bog squares.

Stealth and Detection in a Marsh

In a moor, the maximum distance at which a creature can succeed at a Perception check to detect the presence of others is 6d6×10 feet. In a swamp, this distance is 2d8×10 feet. Vegetation and deep bogs provide plentiful concealment (20% miss chance), so it is possible to use Stealth to hide in a marsh.

Urban Terrain

Urban terrain can be found in most settlements where the people have greatly exerted their influence over the surrounding environment, constructing buildings where they can live and work in comfort and laying well-defined roads, usually paved. This type of terrain can occur in just about any biome, and it often supersedes the environmental effects of that biome. Urban terrain can include space stations, and it is often replete with technology. The most common rules sections to reference when using urban terrain are settlements, structures, and vehicles, as well as Breaking Objects and sometimes Radiation.

Stealth and Detection in Urban Terrain

In a settlement with wide, open streets, the maximum distance at which a creature can succeed at a Perception check to detect the presence of others is 2d6×10 feet. In a settlement where the buildings are more crowded, standing close together, this distance is 1d6×10 feet. The presence of crowds might reduce this distance.

Thanks to twisting side streets and vehicles that can provide cover, it’s usually easy for a creature to use Stealth to hide in a settlement. In addition, settlements are often noisy, making Perception checks that rely on sound more difficult; this increases the DC of any such checks by 2 per 10 feet.


Weather can play an important role in an adventure. The following section describes weather common on most habitable worlds. Additional rules for cold and heat dangers can be found in Environmental Rules.

Rain and Snow

Bad weather frequently slows or halts travel and makes it virtually impossible to navigate from one spot to another. Torrential downpours and blizzards obscure vision as effectively as dense fog. Most precipitation is rain, but in cold conditions it can manifest as snow, sleet, or hail. If the temperature drops from above freezing to 32° F or below, it might produce ice.


Rain reduces visibility ranges by half, resulting in a –4 penalty to Perception checks. It has the same effect on flames and Perception checks as severe wind (see below).


Falling snow has the same effects on visibility and skill checks as rain. Snow-covered squares count as difficult terrain. A day of snowfall leaves 1d6 inches of snow on the ground.

Heavy Snow

Heavy snow has the same effects as normal snowfall but also restricts visibility as fog does (see Fog below). A day of heavy snow leaves 1d4 feet of snow on the ground. Snow at this depth counts as difficult terrain, and it costs 4 squares of movement to enter a square covered with heavy snow. Heavy snow accompanied by strong or severe winds might result in snowdrifts 1d4×5 feet deep, especially in and around objects big enough to deflect the wind—a reinforced wall or a large force field, for instance. There’s a 10% chance that a heavy snowfall is accompanied by lightning (see Thunderstorm).

Other Precipitation

There are other forms of precipitation, such as freezing rain, hail, and sleet. These generally function as rain when falling, but at the GM’s discretion, they may also have effects on movement similar to snow once they accumulate on the ground.


The combined effects of precipitation (or dust) and wind that accompany storms reduce visibility ranges by three-quarters, imposing a –8 penalty to Perception checks. Storms make aiming with ranged weapons difficult, imposing a –2 penalty to attack rolls, and archaic ranged weapons can’t be fired at all. Storms automatically extinguish unprotected flames. Storms commonly appear in three types: dust, snow, or thunder.

Dust Storm

These desert storms differ from other storms in that they have no precipitation. Instead, a dust storm blows fine grains of sand that obscure vision, smother unprotected flames, and can even choke protected flames (50% chance). Most dust storms are accompanied by severe winds and leave behind a deposit of 1d6 inches of sand. There is a 10% chance for a dust storm to be accompanied by windstorm-magnitude winds (see Table 11–6: Wind Effects); this greater dust storm deals 1d3 nonlethal damage each round to anyone caught out in the open without shelter and also poses a choking hazard (see Suffocation and Drowning). A greater dust storm leaves 2d3–1 feet of fine sand in its wake.


In addition to the wind and precipitation common to other types of storms, a snowstorm leaves 1d6 inches of snow on the ground afterward.


In addition to wind and precipitation, a thunderstorm is accompanied by lightning that can pose a hazard to characters who don’t have proper shelter (especially those in metal armor). As a rule of thumb, assume one bolt per minute for a 1-hour period at the center of the storm (GM rolls to hit). Each bolt deals between 4d8 and 10d8 electricity damage. One in 10 thunderstorms is accompanied by a tornado.

Powerful Storms

Very high winds and torrential precipitation reduce visibility to zero, making Perception checks and all ranged weapon attacks impossible. Powerful storms are divided into the following types.

Blizzard: The combination of high winds, heavy snow (typically 1d4 feet), and extreme cold make blizzards deadly for those unprepared for them.

Hurricane: In addition to very high winds and heavy rain, hurricanes are accompanied by floods. Most adventuring activity is extremely difficult under such conditions.

Tornado: With incredibly high winds, tornadoes can severely injure and kill creatures pulled into their funnels.

Windstorm: While accompanied by little or no precipitation, windstorms can cause considerable damage simply through the force of their winds (see Winds below).


Whether in the form of a low-lying cloud or a mist rising from the ground, fog obscures all sight beyond 5 feet, including darkvision. Creatures 5 feet away have concealment (20% miss chance).


Wind can create a stinging spray of dust, sand, or water, fan a large fire, rock an atmospheric transport midflight, and blow gases or vapors away. If powerful enough, it can even interfere with some ranged attacks and knock characters down. Below are the most common wind forces seen on habitable worlds.

Light Wind

A gentle breeze, having little or no game effect.

Moderate Wind

A steady wind often extinguishing small, unprotected flames.

Strong Wind

Gusts that automatically put out any unprotected flames. Such gusts impose a –2 penalty to nonenergy ranged weapon attack rolls.

Severe Wind

Nonenergy ranged weapon attack rolls take a –4 penalty.


Powerful enough to bring down branches, if not whole trees. Nonenergy ranged weapon attack rolls take a –4 penalty, while attacks with archaic ranged weapons are impossible. Perception checks that rely on sound take a –8 penalty due to the howling of the wind. Small characters might be knocked down.

Hurricane-Force Wind

Nonenergy ranged weapon attack rolls take a –8 penalty, and archaic ranged weapon attacks are impossible. Perception checks based on sound are impossible: all characters can hear is the roaring of the wind. Hurricane-force winds often fell trees. Most characters are knocked down due to the force of these winds.


All flames are extinguished. All nonenergy ranged weapon attacks are impossible, as are sound-based Perception checks. A creature in close proximity to a tornado that fails a DC 15 Strength check is sucked toward the tornado. All creatures that come into contact with the actual funnel cloud are picked up and whirled around for 1d10 rounds, taking 6d6 bludgeoning damage per round, before being violently expelled in a random direction (falling damage, described below, might apply). While a tornado’s rotational speed can be as great as 300 mph, the funnel itself moves forward at an average of 30 mph (roughly 250 feet per round). A tornado uproots trees, destroys buildings, and causes similar forms of major destruction.

Table 11–6: Wind Effects
Wind Force Wind Speed Ranged Attack Penalty*
Light 0–10 mph
Moderate 11–20 mph
Strong 21–30 mph –2
Severe 31–50 mph –4
Windstorm 51–74 mph –4
Hurricane 75–174 mph –8
Tornado 175–300 mph Impossible

* This applies only to nonenergy ranged weapons. Larger weapons, such as starship weapons, ignore this penalty.

Environmental Rules

The following is a compilation of rules appropriate for use in a variety of environments.

Cold Dangers

Cold and exposure deal nonlethal damage to the victim. A character can’t recover from the damage dealt by a cold environment until she gets out of the cold and warms up again.

An unprotected character in cold weather (below 40° F) must succeed at a Fortitude save each hour (DC = 15 + 1 per previous check) or take 1d6 nonlethal cold damage. A character can attempt Survival skill checks to gain a bonus to this saving throw and might be able to apply this bonus to other characters as well.

In conditions of severe cold (below 0° F), an unprotected character must succeed at a Fortitude save every 10 minutes (DC = 15 + 1 per previous check) or take 1d6 nonlethal cold damage. A character can attempt Survival skill checks to gain a bonus to this saving throw and might be able to apply this bonus to other characters as well.

Extreme cold (below –20° F) deals 1d6 lethal cold damage per minute (no saving throw). In addition, a character must succeed at a Fortitude save (DC = 15 + 1 per previous check) each minute or take 1d4 nonlethal cold damage. Colder environments can deal more damage at the GM’s discretion.

A character who takes any damage from cold or exposure is beset by frostbite or hypothermia (same as fatigued). These penalties end when the character recovers the nonlethal damage she took from the cold and exposure.

Ice Icy surfaces count as difficult terrain, and the DCs for Acrobatics checks attempted on ice increase by 5. Characters in prolonged contact with ice might run the risk of taking damage from severe cold.


A character that falls takes 1d6 damage per 10 feet fallen, to a maximum of 20d6. A character that takes damage from a fall lands prone.

If a character deliberately jumps instead of merely slipping or falling, the damage is the same but the first 1d6 is nonlethal damage. On a successful DC 15 Acrobatics check, the character avoids taking damage from the first 10 feet fallen and converts the damage from the second 10 feet to nonlethal damage. For example, a character who slips from a ledge 30 feet up takes 3d6 damage. If the same character deliberately jumps, he takes 1d6 nonlethal damage and 2d6 lethal damage. and if the character leaps down with a successful DC 15 Acrobatics check, he takes only 1d6 nonlethal damage and 1d6 lethal damage from the plunge.

The damage from the first 10 feet of a fall onto a yielding surface (such as soft ground or mud) is converted into nonlethal damage. This conversion is cumulative with damage reduced through deliberate jumps and successful Acrobatics checks.

A character can’t cast a spell or activate an item while free-falling unless the fall is greater than 500 feet or the spell or item can be used as a reaction. Casting teleport or a similar spell while falling doesn’t end the character’s momentum; it just changes her location, meaning that she still takes falling damage, even if she arrives atop a solid surface.

Falling and Gravity

The rules for falling presented here assume standard gravity. For planets with high or low gravity, double or halve the damage amounts, respectively. Falling in extreme gravity deals as least triple the listed damage, and potentially even more.

Falling into Water

Falls into water are handled somewhat differently. If the water is at least 10 feet deep, a falling character takes no damage for the first 20 feet fallen and 1d3 nonlethal damage per 10-foot increment for the next 20 feet fallen. Beyond that, falling damage is lethal damage as normal (1d6 per additional 10-foot increment).

A character who deliberately dives into water takes no damage with a successful DC 15 Athletics check or DC 15 Acrobatics check, as long as the water is at least 10 feet deep for every 30 feet fallen. The DC of the check increases by 5 for every 50 feet of the dive.

Falling Objects

Just as characters take damage when they fall more than 10 feet, so too do they take damage when they are hit by falling objects.

An object that falls upon a character deals damage based on its size and the distance it fell. Table 11–7: Damage from Falling Objects determines the amount of damage dealt by an object based on its size. Note that this assumes the object is made of dense, heavy material, such as metal or stone. Objects made of lighter materials might deal as little as half the listed damage, subject to the GM’s discretion. For example, a Huge boulder that hits a character deals 6d6 bludgeoning damage, whereas a Huge wooden wagon might deal 3d6 bludgeoning damage. In addition, if an object falls less than 30 feet, it deals half the listed damage. If an object falls more than 150 feet, it deals double the listed damage. Note that a falling object takes the same amount of damage as it deals.

Dropping an object on a creature requires a ranged attack against its KAC. Such attacks generally have a range increment of 20 feet. If an object falls on a character (instead of being thrown), that character can attempt a DC 15 Reflex save to take half damage if he is aware of the object. Falling objects that are part of a trap use the trap rules instead of these general guidelines.

Table 11–7: Damage from Falling Objects
Object Size Damage
Tiny or smaller 1d6
Small 2d6
Medium 3d6
Large 4d6
Huge 6d6
Gargantuan 8d6
Colossal 10d6


Gravitational differences between planets have the potential to cripple characters or make them superheroes—and sometimes both at the same time. Most planets habitable by humanoids have a gravity level defined as standard, which makes them similar enough that trying to arbitrate the difference isn’t necessary. Others, however, require special consideration. For planets with gravities that aren’t quite standard but don’t fall into the exact categories below, the GM might decide to assume the effects are proportional. For example, a planet with half standard gravity allows player characters to jump twice as high, whereas one with 1-1/2 standard gravity cuts jump heights by a third. In all cases, these effects last until the PCs adjust to the gravity (a process that typically takes about a month of living under such conditions). See Flying for information about flying on planets with high or low gravity.

Extreme Gravity

A planet where the gravity is at least five times as strong as standard gravity is extremely dangerous to most creatures. In addition to the limitations of high gravity (see below), a creature in this environment takes an amount of nonlethal bludgeoning damage per round (at least 1d6, but potentially more, depending on the intensity of the gravity). Once a character takes sufficient nonlethal damage to be reduced to 0 Hit Points, any further damage from extreme gravity is lethal bludgeoning damage.

High Gravity

On high-gravity worlds, characters are burdened by their increased weight, and their physical abilities are affected accordingly. On a high-gravity world, where the gravity is at least twice as strong as standard gravity, a character (and her gear) weighs twice as much as on a standard-gravity world, but she has the same amount of strength. Such characters move at half speed, can jump only half as high or as far, and can lift only half as much. Thrown weapons (though not those of natives) have their ranges cut in half as they fall to the ground more rapidly. Modifications to running, jumping, and lifting can be negated by certain magic or technology, but projectiles remain affected. Characters who remain in a high-gravity environment for long periods (more than a day) often become fatigued and remain so until they leave the planet or become accustomed to the gravity.

Low Gravity

Low-gravity worlds are liberating to most species acclimated to standard-gravity worlds. Such characters’ muscles are far more effective than normal. On a low-gravity world, where the gravity is no greater than a third of standard gravity, PCs can jump three times as high and as far and lift three times as much. (Movement speed, however, stays the same, as moving in great bounds is awkward and difficult to control.) Thrown weapons have their range categories tripled.


Standard-gravity worlds have gravity approximately the same as Earth’s gravity.

Zero Gravity

Movement in zero gravity (also referred to as zero-g) is not the same as flight. Controlled movement is difficult without some form of propulsion, and creatures without something to push off from often find themselves floating aimlessly. A creature in a zero-gravity environment can’t take move actions to move its speed, crawl, or take a guarded step. If a creature is adjacent to or in the same square as an object (including a wall, floor, or ceiling) or another creature one size category smaller than itself or larger, it can take a move action to push off that object or creature, moving at half its land speed in a direction of its choosing (as appropriate); if that object or creature is movable, it begins moving in the opposite direction at that same speed.

Moving in Zero-G: A creature that moves in a given direction continues to move in that direction at the same speed at the beginning of its turn each round (without taking any action); it must move the full distance unless it is able to change its motion by latching on to an object or creature, pushing off in a new direction, or creating thrust of some kind (all of which are considered move actions). If a creature runs into a solid object during its movement, it must succeed at a DC 20 Acrobatics or Athletics check to safely stop its movement; failure means that creature gains the off-kilter condition. If a creature runs into another creature during its movement, both creatures must each attempt a DC 20 Acrobatics or Athletics check to avoid gaining the off-kilter condition. A creature anchored to a solid object (such as by the boot clamps available with most armor) receives a +4 bonus to this check. An off-kilter creature in a zero-gravity environment can steady itself as a move action that requires a surface to grab on to or some method of propulsion; alternatively, that creature can throw a single item weighing at least 4 bulk (for Medium creatures; 2 bulk for Small creatures) to reorient itself and remove the off-kilter condition.

If provided with sufficient handholds, a creature with a climb speed can move along a wall at full speed, as can any creature that succeeds at a DC 20 Acrobatics or Athletics check. Creatures that fly via methods that require an atmosphere, such as wings or turbofans, can’t use their fly speeds in a vacuum; once they reenter an atmosphere, they can recover and get their bearings within 1d4 rounds, after which they can fly normally. Magical flight and methods of flight that provide their own thrust, such as maneuvering jets, are not affected. A character in a zero-gravity environment can lift and carry 10 times her normal amount.

Weapons: Thrown weapons have their range increments multiplied by 10 in zero-g. In addition, all ranged weapons no longer have a maximum number of range increments—their wielders simply continue to accrue penalties the farther away the target is.

Heat Dangers

Heat deals nonlethal damage to the victim. A character can’t recover from the damage dealt by a hot environment until she gets out of the heat and cools off.

A character in very hot conditions (above 90° F) must attempt a Fortitude saving throw each hour (DC = 15 + 1 per previous check) or take 1d4 nonlethal fire damage. Characters wearing heavy clothing or armor of any sort take a –4 penalty to their saving throws. A character can attempt a Survival check to receive a bonus to this saving throw, and might be able to apply this bonus to other characters as well.

In severe heat (above 110° F), a character must attempt a Fortitude saving throw once every 10 minutes (DC = 15 + 1 per previous check) or take 1d4 nonlethal fire damage. Characters wearing heavy clothing or armor of any sort take a –4 penalty to their saves. A character can attempt a Survival check to receive a bonus to this saving throw and might be able to apply this bonus to other characters as well.

Extreme heat (air temperature over 140° F, boiling water, fire, and lava) deals lethal fire damage. Breathing air in extreme heat deals 1d6 fire damage per minute (no saving throw). In addition, a character must attempt a Fortitude saving throw every 5 minutes (DC = 15 + 1 per previous check) or take 1d4 nonlethal fire damage. Hotter environments can deal more damage at the GM’s discretion.

A character who takes any damage from heat exposure suffers from heatstroke (same as the fatigued condition). These penalties end when the character recovers from the nonlethal damage she took from the heat.

Boiling water deals anywhere from 1d6 to 10d6 fire damage per round of exposure, depending on water temperature and level of immersion.

Catching on Fire

Characters exposed to burning oil, bonfires, and noninstantaneous magical fires might find their clothes, hair, or equipment on fire. Spells or technological items with an instantaneous effect don’t normally set a character on fire, since the heat and flame from these come and go in a flash.

A character at risk of catching fire must succeed at a Reflex saving throw (usually DC 15) or gain the burning condition. Those whose clothes or equipment catch fire must attempt a separate Reflex saving throw (at the same DC) for each item. On a failed saving throw, flammable items take the same amount of damage as the character.

Lava Effects

Lava or magma deals a minimum of 2d6 fire damage per round of exposure, while cases of total immersion (such as when a character falls into the crater of an active volcano) deal upward of 20d6 fire damage per round. The exact damage is left to the GM’s discretion, based on situational terrain elements.

Damage from lava continues for 1d3 rounds after exposure ceases, but this additional damage is only half of that dealt during actual contact (that is, 1d6 or 10d6 per round). Immunity or resistance to fire serves as an immunity or resistance to lava or magma. A creature immune or resistant to fire might still drown if completely immersed in lava (see Suffocation and Drowning).


Radiation is a very real threat to adventurers, whether it’s the radiation emitted from stars or the radiation generated by various technological wonders of the universe. Radiation is a poison effect that weakens an affected creature’s Constitution and can also inflict an affected creature with a disease called radiation sickness. Radiation dangers are organized into four categories: low, medium, high, and severe. The effects of these categories of radiation are described on Table 11–8: Radiation Levels.

Area of Effect

Radiation is an emanation poison, meaning that a victim only needs to enter an area suffused with radiation to be affected by it. Radiation suffuses a spherical area of effect that can extend into solid objects. The closer one gets to the center of an area of radiation, the stronger the radiation effect becomes. Radiation entries list the maximum level of radiation in an area, as well as the radius out to which this radiation level applies. The radiation continues to suffuse each increment out to an equal length beyond that radius, its strength degraded by one level per increment. For example, a spherical area of high radiation with a radius of 20 feet creates a zone of medium radiation spanning 20 feet to 40 feet from the center in all directions, and a similar zone of low radiation spanning 40 to 60 feet from the center.

Curing Radiation Effects

A creature that leaves an area suffused with radiation is essentially cured of the poison effect. Ending the source of radiation or successfully casting remove radioactivity has the same effect. As usual for poison effects, an affected creature requires rest to recover from radiation poisoning. Remove affliction doesn’t cure a creature of the effects of radiation poisoning, but remove radioactivity does.

If a creature has been exposed to enough radiation, it might contract radiation sickness, which acts like a noncontagious disease. Symptoms of radiation sickness include nausea, vomiting, and loss of hair. Radiation sickness can be treated like any disease, although it can’t be cured with remove affliction. Remove radioactivity can cure radiation sickness.


Type poison, emanation (see above); Save Fortitude (see chart)

Track Constitution; Frequency 1/round

Effect At each state of impaired and beyond, the victim must succeed at a DC 18 Fortitude saving throw or contract the radiation sickness disease (see below).

Cure none

Radiation Sickness

Type disease; Save Fortitude (same DC as the level of radiation that caused the radiation sickness)

Track physical; Frequency 1/day

Effect Radiation sickness isn’t contagious.

Cure 3 consecutive saves

Table 11–8: Radiation Levels
Radiation Level Fort DC
Low 13
Medium 17
High 22
Severe 30

Sleep Deprivation

A character who needs to sleep must get at least 6 hours of sleep every night. If she doesn’t, she must attempt a Fortitude save (DC = 15 + 1 per previous check) after each night she doesn’t sleep enough. The first failed check causes her to become fatigued and take a –1 penalty to saving throws against effects that cause the asleep condition. A second failed check causes her to become exhausted, and the penalty to saving throws against effects that cause the asleep condition increases to –2.

Smoke Effects

A character who inhales heavy smoke must attempt a Fortitude save each round she’s within the smoke (DC = 15 + 1 per previous check) or spend that round choking and coughing. A character who chokes for 2 consecutive rounds takes 1d6 nonlethal damage. Smoke obscures vision, giving concealment (20% miss chance) to characters within it.

Starvation and Thirst

Characters might find themselves without food or water and with no means to obtain them. In normal climates, Medium characters need at least a gallon of fluids per day to avoid thirst and about a pound of decent food per day to avoid starvation; Small characters need half as much. In very hot climates, characters need two or three times as much water to avoid thirst.

A character can go without water for 1 day plus a number of hours equal to his Constitution score. After this time, the character must succeed at a Constitution check each hour (DC = 10 + 1 per previous check) or take 1d6 nonlethal damage.

A character can go without eating food for 3 days. After this time, the character must succeed at a Constitution check (DC = 10 + 1 per previous check) each day or take 1d6 nonlethal damage.

A character who has taken any damage from lack of food or water is fatigued. Damage from thirst or starvation cannot be recovered until the character gets food or water, as needed—not even magic that restores Hit Points heals this damage.

Suffocation and Drowning

A character who has no air to breathe can hold her breath for a number of rounds equal to twice her Constitution score. If a character takes a standard or full action, the remaining duration that the character can hold her breath is reduced by 1 round. After these rounds have elapsed, the character must attempt a Constitution check (DC = 10 + 1 per previous check) each round in order to continue holding her breath.

When the character fails one of these Constitution checks, she begins to suffocate. In the first round, she is reduced to 0 Hit Points and is unconscious and stable. In the following round, she is no longer stable and begins dying. In the third round, she suffocates and dies.

An unconscious character must begin attempting Constitution checks immediately upon losing air supply (or upon becoming unconscious, if the character was conscious when her air was cut off). Once she fails one of these checks, she immediately drops to 0 Hit Points and is dying. On the following round, she suffocates and dies.

Slow Suffocation

A Medium creature can breathe easily for 6 hours in a sealed cubic chamber measuring 10 feet on a side. After that time, the creature takes 1d6 nonlethal damage every 15 minutes.

Each additional Medium creature or significant fire source (a torch, for example) proportionally reduces the time the air will last (two Medium creatures will run out of air in 3 hours, and so on). Small characters consume half as much air as Medium characters. A creature stuck in a starship or space station whose life support systems have completely failed will run out of breathable air in a similar fashion; while these structures are often larger than a 10-foot cube, they are also often occupied by several creatures. On average, a crew of four in a Medium starship without a source of fresh air can breathe easily for 20 hours.

Underwater Combat

Land-based creatures usually have considerable Difficulty when fighting in water, as it affects a creature’s attack rolls, damage, and movement. The following adjustments apply whenever a character is swimming, walking in chest-deep water, or walking along the bottom of a body of water.

Attacks from Land

Characters swimming or floating in water that is at least chest deep and characters who are fully immersed have cover against attacks made from the surface.

Attacks Underwater

Most attacks made underwater take a –2 penalty and deal half damage. Attacks that deal fire damage do only one-quarter damage. Attacks that deal electricity damage take a –4 penalty rather than a –2 penalty. Melee attacks that deal piercing damage deal full damage. Thrown weapons are ineffective underwater, even when launched from land.

Spellcasting Underwater

A creature that is attempting Constitution checks to hold its breath can’t concentrate enough to cast spells. Some spells might work differently underwater, subject to the GM’s discretion.