Mancubi are quite rare, and only appear in 2 levels in Doom 3. They first appear in a sort of "mini-boss" fight against 3 Mancubi in Recycling Sector 2 (possibly mirroring the Mancubus' introduction in Doom II's [[MAP07: Dead Simple (Doom II)|seventh level]]), and several are also encountered throughout Hell. They also appear in ''[[Resurrection of Evil]]'', although again they are mostly confined to Hell.
The Doom 3 Mancubus has ''extremely'' high offensive capabilities. Though it can only fire one cannon at a time unlike its classic counterpart, it more than makes up for this by being able to fire a steady barrage of powerful fireballs from each cannon, unlike the classic version, which can only fire three volleys from both cannons at once. It is also tougher than the classic version, taking 2 to 3 magazines of [[Machine Gun]] fire, a full magazine of Chaingun or Plasma Gun fire, or as many as six direct rocket hits to kill, making it the toughest (but also one of the slowest) non-boss creature in the game.
Furthermore, unlike the classic Mancubus, the Doom 3 version has a melee attack: both of its cannons can be used as hammers, which while attacking almost spontaneously, it is possible to use its long "recharge" time to actually kill the Mancubus with any melee weapon ([[Chainsaw (Doom 3)|chainsaw]] being the best bet). However, melee combat is not advisable as the Mancubus' crushing melee smash is one of the most powerful enemy melee attacks in the game, second only to the [[Cyberdemon (Doom 3)|Cyberdemon]]'s stomp.
Mancubi are real powerhouses, with extremely high health and a powerful ranged attack with a reasonably high rate of fire. Players are fully justified in using their most high-powered weaponry to bring one down. The weapons that are effective against the Mancubus are the [[Chaingun (Doom 3)|Chaingun]], the [[Rocket launcher (Doom 3)|Rocket launcher]], [[Plasma Gun]], and the [[BFG 9000 (Doom 3)|BFG]]. [[Grenade]]s also work well due to the lumbering speed of these behemoths. Headshots are effective and quite easy to score on a Mancubus, since they are a slow moving and very large target. A Mancubus can be killed with about 4 rocket launcher headshots. If the [[Soul Cube]] or [[The Artifact|Artifact]] is available, by all means use it.