Mancubus/Doom II

The Mancubus (plural: Mancubi) is a monster introduced in Doom II MAP07: Dead Simple, where the player is forced to fight a group of them to break through a fortified area controlled by the demons.

Appearance
The Mancubus is a large, cybernetic humanoid monster shambling about on sturdy, stumpy elephant-like legs with six toes, three on the front and three on the back for each, glaring at opponents through hateful green eyeballs without irises or pupils, with a bloody mouth that displays sharp yellow fangs. Its arms consists of huge flamethrowers, capable of spouting a rapid series of scathing fireballs powered by a pair of fuel tanks grafted directly onto the obese monster's back.

The game manual describes the Mancubus as follows: "The only good thing about fatso is that he's a nice wide target. Good thing, because it takes a lot of hits to puncture him. He pumps out fireballs like there was no tomorrow."

A Mancubus will make a gurgling/snorting sound that goes in crescendo into a short, monstrous tiger-like snare, when spotting a player. When shot at, a Mancubus utters a deep low-pitched moan, and when killed, it lets out a low-pitched exhale of air. Its head is split in two and its top half blasted apart, breaking in half the fuel tubes near it. Its body then begins to slowly divide in half, the skin and flesh tearing open and shriveling inwards, unleashing deluges of blood, until all that remains are folds of ripped flesh, blood-soaked bones and ribs, and its green eyeballs spilling out between the two disembodied fireball launchers. This is quite possibly the goriest death sequence of any enemy.

Tactical analysis
Mancubi are dangerous opponents, but have a number of exploitable weaknesses. They are slow, and make large targets, so are easy to kill with rapid-fire weapons. Much like Cacodemons, Mancubi have a high pain chance and generally aren't able to fire when under attack from a chaingun or plasma rifle. The rocket launcher is possibly the most effective weapon against the Mancubi. Furthermore, because they pause briefly before attacking, and also give out their distinctive "come tomorrow" battle cry before firing, it is pretty easy to prevent them from attacking using slower weapons, even the super shotgun. When they do attack, it is helpful to attempt to keep one's distance. Otherwise, the player might end up taking two fireballs instead of just one. When dodging from a greater distance, it is important to avoid over-dodging. With the first two attacks from the Mancubus, one fireball will go straight toward the player while the other will fly off diagonally to the other side (left or right, depending on the player's location); in the third volley, one will go left and one right. This pattern can be figured out and used to avoid Mancubus attacks.

Once a Mancubus has begun to attack its target, it continues to fire (if it remains unhurt while firing) until all six bursts have been discharged, even if the target has moved out of its sight. This characteristic of their attack can be abused to cause monster infighting. Their huge build and high pain chance can afford a player an opportunity to conserve ammo and health by using a Mancubus as a "living shield". This tactic can be risky, but in a situation of other monsters, especially when there are Chaingunners or Arachnotrons lurking near a Mancubus, it can work to the player's advantage.

Data

 * 1) This table assumes that all calls to P_Random for damage, pain chance, impact animations, and backfire checks are consecutive. In real play, this is never the case: counterattacks and AI pathfinding must be handled, and of course the map may contain additional moving monsters and other randomized phenomena (such as flickering lights). Any resulting errors are probably toward the single-shot average, as they introduce noise into the correlation between the indices of "consecutive" calls.
 * 2) Assumes that direct hits are possible, which does not occur in any stock map.
 * 3) Hardcoded exception to infighting negates damage (excepting indirect damage caused by exploding barrels).

Appearance statistics
In classic Doom, the Mancubus is first encountered on these maps:

The IWADs contain the following numbers of Mancubi: