The Revenant

Revenants are monsters introduced in Doom II that are easily recognized by their high-pitched shriek. They take the form of very tall animated skeletons in silver metal body armor equipped with shoulder-mounted missile launchers, and blood and gore running down their legs. Their running movements are a herky-jerky approach akin to a stringed puppet.

A revenant emits a loud, high-pitched, hollow scream when spotting the player.

Revenants fire two varieties of missiles, unguided and homing. The homing missiles can be distinguished by a gray smoke trail. During melee combat they can also strike a blow with one of their large fists, complete with an exaggerated punching sound effect. Revenants have a unique characteristic unlike any other monster that has a melee attack: when the distance to its target is less than 196 units, the revenant abandons its missile attack completely and attempts to close to melee range; if attacked and hurt however, it will still immediately counter-attack with a single missile.

A revenant fires an unguided missile on odd game tics and homing missiles on even game tics, with a 1 in 4 chance of inverted behavior due to RNG off-set. In practice since the vast majority of a revenant's animations last an even number of frames, any given revenant will favor one type of missile with a 3-1 ratio unless they are injured (as their pain animation does have an odd duration if not interrupted), or contact is broken.[1]

When killed, a few of the revenant's bones will shatter and the monster will simply fall on its back, one of the cleanest monster deaths the player will come across.