Arachnotron/Doom II

"Maybe cybernetics wasn't such a great idea after all. Look what the demons have done with it. It seems unfair somehow you're not the only guy in Hell with a plasma gun."

- Description in the Doom II manual

The Arachnotron is a monster introduced in Doom II. They make their first appearance in MAP07: Dead Simple, where the player must fight a large swarm of them after defeating a pack of Mancubi.

Physical appearance
The Arachnotron is similar in appearance to the Spiderdemon, but smaller and with large blue eyes by default, that change color depending on the monster's current state (moving, hurt, or attacking). Its body consists primarily of a large brain along with two small arms, that is supported by a metal chassis with four mechanical legs.

Combat characteristics
An Arachnotron emits a crescendo-ing mechanical cry (akin to machinery powering up) when spotting a player. Like the Spiderdemon, it has audible footsteps, in their case sounding like buzzing machinery punctuated with occasional electronic crackling.

Instead of the chaingun like the Spiderdemon, the Arachnotron has a powerful plasma gun installed on its chassis that fires quick bursts of yellow and green energy. Once the Arachnotron engages an enemy, it will continue to fire until the enemy is killed or moves out of its field of view, or until the monster itself flinches in pain or is destroyed - similar behavior can be observed with the Spiderdemon, Wolfenstein SS and Heavy Weapon Dude.

When this monster dies, its head explodes into a morass of gore as its mechanical body collapses while unleashing an electronically-pitched dying tone that resembles failing machinery.

Tactical analysis
The multiple bursts from the Arachnotron's plasma shots can be quite devastating. And their habit of continuously firing at their enemy upon first sight of them can make short work on an inexperienced player. Furthermore, their plasma bursts are among the fastest projectiles, and it can obscure the player's vision upon a successful hit. The best course of action is once you see the Arachnotron firing it's shots, do not stay at one place. Instead immediately move out of the way and find cover to stop it from continuously firing.

While the Arachnotron's plasma shots are pretty powerful, their projectiles are also wide enough that narrow obstacles can sometimes act as excellent cover from their shots. If the player can get close to the monster and position themselves on a higher plane by standing on a platform, the Arachnotron will repeatedly fire, but their plasma shots will only dissipate on the top edge of the platform, rendering the player safe from harm.

The basic strategy to take out an Arachnotron is from range. As players are able to read the trail of the Arachnotron's plasma bursts from a distance, this can serve as a good indicator for the player to avoid their shots without taking damage. The rocket launcher is an effective long range weapon as it takes two-three rockets to completely destroy an Arachnotron. The repeating shots from the plasma gun can also work wonders as Arachnotrons have a medium pain chance, making couple of initial plasma shots to stun them.

Although they may seem slow, Arachnotrons are actually faster than quite a few of the other monsters and can catch up with the player at an alarming rate. If the player must resort to fighting them at close range, the chaingun can work well. A skilled player can also rely on using the super shotgun to take them down at point blank range. However, this will require players to circle around the monster as it takes two-three point blank shots to completely obliterate them.

Because of their sustained, extremely fast rate of fire, they are often more than capable of defeating almost any monster if provoked via monster infighting, especially when multiple Arachnotrons attack; however, stronger enemies like the Mancubus would even out the fight, given that it also displays near identical behavior to the Arachnotron as well having attacks just as potent. A Baron of Hell will usually prevail in smaller battles because of their higher health.

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).

Trivia
The Arachnotron's sprites have numerous holes in them.

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

The IWADs contain the following numbers of Arachnotrons: