Mancubus/Doom II

"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."

- Doom II instruction manual

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.

Physical 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.

Combat characteristics
The Mancubus primarily attacks by launching three volleys of fireballs from it's twin flamethrowers. Once a Mancubus has begun to attack its target, it continues to fire until all six bursts have been discharged, even if the target has moved out of its sight.

Upon spotting the player, the Mancubus will make a gurgling/snorting sound that goes in crescendo into a short, monstrous tiger-like snare. When shot at, the Mancubus will 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 and their fireballs can easily annihilate a careless player. However, they have a number of exploitable weaknesses.

The Mancubus' lumbering speed and large, wide stature make the super shotgun a very effective weapon, as most if not all of the pellets can connect and hit the monster at point blank range.

Alternatively, like Cacodemons, the Mancubi have a high pain chance, thus making them vulnerable to repeating weapons as they aren't able to fire when under attack from a chaingun or plasma rifle.

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's attacks.

If the player is not too confident in taking out a Mancubus up close, they can also rely on the rocket launcher to take them out from range. Given that the Mancubus presents itself as a large target, it generally takes two to three rockets to completely take them down, depending on the splash damage they receive.

The Mancubi's habit of launching their attacks even when their target is out of range can be abused to cause monster infighting. The Mancubus presents itself as a formidable opponent against many other monsters, standing in equal to the higher level demons like the Arachnotron and the Baron of Hell. 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: