Hazards in Combat
Source GM Core pg. 78
In isolated encounters where the PCs have plenty of time to recover from hazards' effects, simple hazards can feel more like speed bumps than true challenges. But when combined with other threats, even simple hazards can prove perilous. A noisy explosion can draw attention, allowing foes to burst through the door for a dramatic start to the encounter. Radiation is especially tricky as it can cause the PCs' gear to glitch, which can be especially devastating in encounters where the PCs rely on tech gear to move, such as jetpacks, or attack enemies who are far away. Simple hazards can also be an active part of an encounter, particularly if the foes know how to avoid triggering them.
As their name suggests, complex hazards are a more powerful tool for encounters. Because they continue to act, they're an ongoing presence in the fight. When combined with hostile creatures, complex hazards offer the PCs plenty of choices for what they want to do next. This is particularly true if foes benefit from the hazard. Should the PCs first disable the array of pipes spewing flammable gas into the room, or should they prioritize the fire elemental creeping closer and closer to the growing cloud of explosive fumes? There's no right answer, and the PCs' choices have a clear impact on the obstacles they face. Hazards in combat shine when they give the PCs ways to contribute meaningfully other than dealing damage to a creature. Interesting actions to disable a hazard are a fun way to give several PCs something fresh and different to do rather than piling on damage.
As their name suggests, complex hazards are a more powerful tool for encounters. Because they continue to act, they're an ongoing presence in the fight. When combined with hostile creatures, complex hazards offer the PCs plenty of choices for what they want to do next. This is particularly true if foes benefit from the hazard. Should the PCs first disable the array of pipes spewing flammable gas into the room, or should they prioritize the fire elemental creeping closer and closer to the growing cloud of explosive fumes? There's no right answer, and the PCs' choices have a clear impact on the obstacles they face. Hazards in combat shine when they give the PCs ways to contribute meaningfully other than dealing damage to a creature. Interesting actions to disable a hazard are a fun way to give several PCs something fresh and different to do rather than piling on damage.