Telefrag

A telefrag is a special kind of frag or kill that results when a player or monster stands on the location of a teleporter as another player teleports to that location. The monster or player who was originally standing at that location will instantly die. Telefrags can be strategically used by a Doom player to kill powerful monsters without using any ammo. Monsters are usually not allowed to teleport to a space that is occupied, preventing them from telefragging. The only exceptions to this are spawn shooter cubes, which telefrag anything on the spot they land on.

Utilizing an intentional telefrag is considered cheating in a UV pacifist speedrun.