Trap room is example of offensive building design.
Usually its a dead-end location that contains mostly traps and spawns monsters.
Elements of design:
1.Bait: something interesting to lure player in. Possibly inaccessible treasure, lever or item prominently displayed.
2.Traps: main offensive feature, activates as the player tries to reach bait.
3.Spawner: spawn monsters, usually to cut off retreat options. Activates after traps, not visually prominent or part of bait mechanism.