Pain elemental

The pain elemental is a Doom II monster that is similar to the cacodemon; they are both floating spheres with a single eye and a large toothy mouth. The main differences in respect to its counterpart are that its hide is leathery brown, it has two small arms akin to the spiderdemon's pair of limbs, and is crowned by only two dark curved horns (similar to the cyberdemon's horns) on the top of its spherical body.

The Doom II manual describes the monster this way: ''What a name. And what a guy. Killing him is almost as bad as letting him live.''

Combat characteristics
A pain elemental emits a strange, hissing babble upon spotting a player. Instead of shooting a standard projectile, the pain elemental periodically spews lost souls at its opponents from a mouth that flares up with a reddish glow each time one of the minions is delivered. As it does not attack directly, the spherical monster will never be targeted by other monsters, though they may unleash lost souls that will attack monsters that hurt them, at least temporarily. The pain elemental is vulnerable to misdirected attacks from its own children, and will retaliate against them.

The lost souls produced by the pain elemental will begin their existence with a charge forwards, after which it will float about a bit until it attacks again. This initial charge will hurt the target, unless avoided. If the lost soul is shot into a wall or a thing from close range when it is produced, it will explode, and if it is created beyond a wall, it may be trapped on the other side.

In any event, the designers set a limit to the monster's attack, so as to not overpopulate a level with lost souls, making it overly dangerous or resource consuming. If there are 21 or more lost souls in a level, pain elementals will not produce their projectile when they attack. They go through the attack sequence without any effect.

When killed, the pain elemental collapses in on itself and explodes, spawning three lost souls. Unlike the cacodemon, the pain elemental does not generally leave behind a corpse. The only exception occurs when a pain elemental is crushed while it is dying, in which case it will leave a small pool of gibs. The gibs can be resurrected by an arch-vile, creating a ghost monster as a result. This event is one of the most rare occurrences in the game.

The pain elemental is one of two monsters (the other being the lost soul), that does not under normal circumstances (see ghost monsters for the exception) leave a corpse and hence it will not respawn when the Nightmare! skill level is chosen or the -respawn parameter is used.

Tactical analysis
Pain elementals move at the same speed as cacodemons and have a similar pain chance and hit points, but are prone to produce much more havoc with their attack, being potentially more dangerous than their red counterparts. Unlike the cacodemon, whose attacks may simply be dodged, pain elementals release projectiles which will come around for more attacks and which will not disappear until killed. As such, it is vital to focus one's attention on the pain elemental itself as much as possible. Fast-firing weapons such as the chainsaw, chaingun or plasma gun work fairly well and usually keep its lost souls at bay, but the rocket launcher is not recommended as the pain elemental may spit a lost soul while the rocket is en route, potentially causing blast damage to the player. Only once it is dead is it recommended to begin killing its minions. If the player finds themselves over-swarmed with lost souls and cannot take a clear shot at its parent, the BFG9000 can easily clear them out and, should the blast be point-blank (or close enough), chances are it will kill the pain elemental as well.

Pain elementals will only spawn lost souls when in line of sight of the player, or another monster who struck it. Therefore an effective tactic against the pain elemental is to deliver a strong attack, then quickly head for cover. In common with the arachnotron and spiderdemon, the pain elemental has a relatively wide character sprite, which allows the player to chip away at its flanks without entering the elemental's line of sight.

Also, there is another tactic to revert the tide of the battle in favor of the player while avoiding the spawn of any lost souls: if the monster opens its mouth at zero distance from the player, i.e. directly at the player's face, the lost soul spawned will be instantly destroyed. The same tactic, however, does not apply to the monster's death: even if the player is occupying the same area of the pain elemental's explosion animation, one or more lost souls resulting from the explosion will still be produced.

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

The IWADs contain the following numbers of pain elementals:

Doom 64
. The pain elemental appears in Doom 64 with an altered design. It is colored red (like the original cacodemon while the Doom 64 cacodemon was colored brown and had two arms), has a green eye and in place of its arms are two mouths so it can now spawn two lost souls at the same time. Its back has a large horse-like mane. It gives off a low sinister laugh when it has sighted the player. When killed, its exploding body can actually hurt the player if he is too close.

Doom RPG
The pain elemental appears in Doom RPG as a class of monster. There are three variations, identified by color:


 * Beholder (green)
 * Rahovart (blue)
 * Pain elemental (normal colors)

They, however, do not spawn lost souls when they attack; only when they are killed. They are particularly weak against attacks from captured hellhounds.

Demo

 * [[Media:RESRPAIN.WAD|A level demonstrating how a pain elemental can be resurrected, despite normally never leaving a body behind when it dies, as a ghost monster]] (file info). Step on button 1 to activate the crusher and wait for the pain elemental to die, and then step on button 2 to stop the crusher when it is near the ceiling. After that, step on button 3 to release the arch-vile and witness the resurrection.