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, but this rule does not take effect on MAP30.

Utilizing an intentional telefrag is considered cheating in a UV_pacifist speedrun.