Brogue Wiki
Pressure plate

A primitive pressure plate, not native to the Dungeons of Doom.

A pressure plate is one component of a trap. It is normally hidden from view until discovered by searching or it is triggered. It will be triggered when you step onto it, a monster steps onto it, or an item is thrown onto it. A pressure plate will almost always trigger a trap, commonly causing harmful gas to flood the area from nearby floor vents. Therefore, if you discover a hidden floor vent a pressure plate can't be too far away.

A flying or floating creature cannot trigger a pressure plate, and the player cannot trigger them whilst levitating. An ally will not step on any pressure plate known to the player (unless confused).

There is one key room that is solved by throwing an item onto a pressure plate. This is the only instance in which a pressure plate does not trigger a trap.

Pressure plates can occasionally be hidden from the players view by flames , nets , bloodwort pods (maybe other stuff). This is a limitation of Brogue's display capacity. If the pressure plate is know to the Rogue, the player will be given an "Are you sure? Yes/No" prompt before accidentally stepping on the plate and triggering the trap (again).