Voodoo doll

Voodoo Doll is the term used when more than one "Player 1 Start" Thing exists on a map in vanilla Doom. Each extra Player 1 start will have a dormant player in its place. When these dormant players are damaged in any way, the actual player will suffer identical damage, hence the name "Voodoo Doll". These can be used for tricks on maps, such as "instant-death teleporters".

The PWAD nopanic2.wad, from Maximum Doom, contains a voodoo doll. If you shoot at the dormant player, you may push him into the nearby teleporter, and he will teleport. If you then follow him into the teleporter, you will self-telefrag.

The PWAD mkfrgtme.wad, also from Maximum Doom, has a voodoo doll already positioned at a teleport landing on the western side of the map. If you use the corresponding teleporter, you will die instantly.