Triggering a Hazard

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 might 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, an electric fence can shock multiple creatures per round.

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 aren't 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, depends on the hazard.

Some hazards can be reset, allowing them to be triggered again. This can occur automatically, as for psychotropic spores, which regrow over the course of 2 weeks. In some cases, you might design a trap that must be reset manually, such as a grenade launcher turret that must be reloaded after being triggered.