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Chapter 10: Game Mastering


Source Core Rulebook pg. 520 4.0
Dungeons are rife with devious traps meant to protect the treasures within. These range from mechanical devices that shoot darts or drop heavy blocks to magic runes that explode into bursts of flame. In addition to traps, adventurers may stumble into other types of hazards, including naturally occurring environmental hazards, mysterious hauntings, and more.

Detecting a Hazard

Source Core Rulebook pg. 520 4.0
Every hazard has a trigger of some kind that sets its dangers in motion. For traps, this could be a mechanism like a trip wire or a pressure plate, while for an environmental hazard or haunt, the trigger may simply be proximity. When characters approach a hazard, they have a chance of finding the trigger area or mechanism before triggering the hazard. They automatically receive a check to detect hazards unless the hazards require a minimum proficiency rank to do so.

During exploration, determine whether the party detects a hazard when the PCs first enter the general area in which it appears. If the hazard doesn’t list a minimum proficiency rank, roll a secret Perception check against the hazard’s Stealth DC for each PC. For hazards with a minimum proficiency rank, roll only if someone is actively searching (using the Search activity while exploring or the Seek action in an encounter), and only if they have the listed proficiency rank or higher. Anyone who succeeds becomes aware of the hazard, and you can describe what they notice.

Magical hazards that don’t have a minimum proficiency rank can be found using detect magic, but this spell doesn’t provide enough information to understand or disable the hazard—it only reveals the hazard’s presence. Determining a magical hazard’s properties thoroughly enough to disable it requires either the use of more powerful magic or a successful skill check, likely using Identify Magic or Recall Knowledge. Magical hazards with a minimum proficiency rank cannot be found with detect magic at all.

Triggering a Hazard

Source Core Rulebook pg. 520 4.0
If the group fails to detect a hazard and the hazard’s trigger is a standard part of traveling (such as stepping on a floor plate or moving through a magical sensor while walking), the hazard’s reaction occurs. Hazards that would be triggered only when someone directly manipulates the environment—by opening a door, for example—use their reactions only if a PC explicitly takes that action.

Reaction or Free Action

Source Core Rulebook pg. 520 4.0
Most hazards have reactions that occur when they’re triggered. For simple hazards, the reaction is the entirety of the hazard’s effect. For complex hazards, the reaction may also cause the hazard to roll initiative, either starting a combat encounter or joining one already in progress, and the hazard continues to pose a threat over multiple rounds. Some hazards have a triggered free action instead of a reaction; for instance, quicksand can suck down multiple creatures per round.


Source Core Rulebook pg. 520 4.0
A complex hazard usually follows a set of preprogrammed actions called a routine. Once triggered, the hazard first performs its initial reaction; then, if the PCs are not yet in encounter mode, they should roll initiative. (If they’re already in encounter mode, their initiative remains the same.) The hazard might tell you to roll initiative for it—in this case, the hazard rolls initiative using its Stealth modifier.

After this happens, the hazard follows its routine each round on its initiative. The number of actions a hazard can take each round, as well as what they can be used for, depend on the hazard.

Resetting a Hazard

Source Core Rulebook pg. 520 4.0
Some hazards can be reset, allowing them to be triggered again. This can occur automatically, as for quicksand, whose surface settles after 24 hours, or manually, like a hidden pit, whose trapdoor must be closed for the pit to become hidden again.

Disabling a Hazard

Source Core Rulebook pg. 521 4.0
The most versatile method for deactivating traps is the Disable a Device action of the Thievery skill, though most mechanical traps can also simply be smashed, and magical traps can usually be counteracted. Environmental hazards often can be overcome with Nature or Survival, and haunts can often be overcome with Occultism or Religion. The specific skill and DC required to disable a hazard are listed in the hazard's stat block. Like using Disable a Device, using these skills to disable a trap is a 2-action activity with the same degrees of success, though the activity might have different traits determined by the GM. As with detecting a hazard, disabling a hazard might require a character to have a certain proficiency rank in the listed skill.

A character must first detect a hazard (or have it pointed out to them) to try to deactivate it. They can attempt to deactivate a hazard whether or not it has already been triggered, though some hazards no longer pose a danger once their reactions have occurred, especially if there is no way for them to be reset.

For most hazards, a successful check for the listed skill against the DC in the stat block disables the hazard without triggering it. Any other means of deactivating the hazard are included in the hazard's stat block, as are any additional steps required to properly deactivate it. A critical failure on any roll to disable a hazard triggers it, including a critical failure on a roll to counteract a magical hazard.

Some hazards require multiple successful checks to deactivate, typically because they have a particularly complicated component or have several discrete portions. For hazards with a complex component, a critical success on a check to disable the hazard counts as two successes on a single component.

Damaging a Hazard

Source Core Rulebook pg. 521 4.0
Rather than trying to carefully disable a hazard, a character might just smash it. Damaging a mechanical trap or another physical hazard works like damaging objects: the hazard reduces the damage it takes by its Hardness. In most cases, hitting the hazard also triggers it, as explained in Attacking a Hazard below. If a hazard’s Hit Points are reduced to its Broken Threshold (BT) or lower, the hazard becomes broken and can’t be activated, though it can still be repaired. If it’s reduced to 0 HP, it’s destroyed and can’t be repaired. (See page 272 in Chapter 6 for more information on damaging objects.)

Hazards’ AC, applicable saving throw modifiers, Hardness, HP, and BT are listed in their stat blocks. A hazard that doesn’t list one of these statistics can’t be affected by anything targeting that statistic. For example, a hazard that has HP but no BT can’t be broken, but can still be destroyed. Hazards are immune to anything an object is immune to unless specifically noted otherwise, and they can’t be targeted by anything that can’t target objects. Some hazards may have additional immunities, as well as resistances or weaknesses.

Attacking a Hazard

Source Core Rulebook pg. 521 4.0
If someone hits a hazard—especially if it’s a mechanical trap—they usually trigger it, though you might determine otherwise in some cases. An attack that breaks the hazard might prevent it from triggering, depending on the circumstances. If the hazard has multiple parts, breaking one part might still trigger the trap. For example, if a trap has a trip wire in one location and launches an attack from another location, severing the trip wire could still trigger the attack. Destroying a trap in one blow almost never triggers it. These rules also apply to most damaging spells or other effects in addition to attacks.

Repairing a Hazard

Source Core Rulebook pg. 521 4.0
You might allow a character to repair a damaged hazard to restore its functionality. You determine the specifics of this, since it can vary by trap. The Repair action might be insufficient if fixing the trap requires gathering scattered components or the like. If the item has a Reset entry, the character needs to do whatever is listed there, in addition to repairing the damage.

Counteracting a Magical Hazard

Source Core Rulebook pg. 521 4.0
Some magical hazards can be counteracted using dispel magic. These hazards’ spell levels and counteract DCs are listed in their stat block. Counteracting a hazard otherwise works like using a skill check to disable the hazard.

Hazard Experience

Source Core Rulebook pg. 521 4.0
Characters gain Experience Points for overcoming a hazard, whether they disable it, avoid it, or simply endure its attacks. If they trigger the same hazard later on, they don’t gain XP for the hazard again. The XP values for hazards of different levels also appear on page 508, but are repeated here for convenience. The XP for a complex hazard is equal to the XP for a monster of the same level, and the XP for a simple hazard is one-fifth of that. Hazards of a lower level than the party’s level – 4 are trivial and award no XP.

Table 10-14: Hazard XP

XP Award
LevelSimple HazardComplex Hazard
Party level -42 XP10 XP
Party level -33 XP15 XP
Party level -24 XP20 XP
Party level -16 XP30 XP
Party level8 XP40 XP
Party level +112 XP60 XP
Party level +216 XP80 XP
Party level +324 XP120 XP
Party level +430 XP150 XP

Hazard Format

Source Core Rulebook pg. 522 4.0
Hazards are presented in a stat block format similar to those used for monsters. A few notes regarding the format follow the sample stat block.

Hazard Name Hazard [Level]

Stealth This entry lists the Stealth modifier for a complex hazard’s initiative or the Stealth DC to detect a simple hazard, followed by the minimum proficiency rank to detect the hazard (if any) in parentheses. If detect magic can be used to detect the hazard, this information is located here as well.
Description This explains what the hazard looks like and might include special rules.
Disable The DC of any skill checks required to disable the hazard are here; if the hazard can be counteracted, its spell level and counteract DC are listed in parentheses.
AC the hazard’s AC; Saving Throws the hazard’s saves. Usually only haunts are subject to Will saves.
Hardness the hazard’s Hardness; HP the hazard’s Hit Points, with its Broken Threshold in parentheses; Immunities the hazard’s immunities; Weaknesses the hazard’s weaknesses, if any; Resistances the hazard’s resistances, if any
Action Type [reaction] or [free-action] This is the reaction or free action the hazard uses; Trigger The trigger that sets off the hazard appears here. Effect For a simple hazard, this effect is often all the hazard does. For a complex hazard, this might also cause the hazard to roll initiative.
Routine This section describes what a complex hazard does on each of its turns during an encounter; the number in parentheses after the word “Routine” indicates how many actions the hazard can use each turn. Simple hazards don’t have this entry.
Action Any action the hazard can use appears here. Typically, this is a melee or ranged attack.
Reset If the hazard can be reset, that information is here.

Level-Based DCs

Source Core Rulebook pg. 522 4.0
The hazard’s level indicates what level of party it’s a good challenge for. If the hazard involves a toxin, curse, or other non-spell feature, that feature’s level is the hazard’s level.


Source Core Rulebook pg. 522 4.0
The most notable hazard traits are trap (constructed to harm intruders), environmental (natural hazards), and haunt (spectral phenomena). Traps have a trait to indicate whether they're magical or mechanical. Hazards that have initiative and a routine have the complex trait.

Stealth or Stealth DC

Source Core Rulebook pg. 522 4.0
Complex hazards list their Stealth modifier, which they use for initiative, instead of their Stealth DC. If you need the DC, it’s equal to this modifier + 10.

Simple Hazards

Source Core Rulebook pg. 522 4.0
A simple hazard uses its reaction only once, after which its threat is over unless the hazard is reset.

Complex Hazards

Source Core Rulebook pg. 526 4.0
Complex hazards function similarly to monsters during encounters, as they roll initiative and have actions of their own, though these are usually automated in a routine.