Mancubus fireball clipping
From DoomWiki.org
A Mancubus, once it has begun to attack the player, normally continues to fire until all six projectiles have been discharged, even if the player has moved out of sight. This can be used for monster infighting, with the jack in the box technique.
A wall, pillar, or other solid object usually blocks the fireballs, but not always; from time to time, a fireball will fly straight through an apparently permanent feature, possibly ambushing an unwary player on the other side.
