Arachnotron

The arachnotron is a spider-like monster introduced in Doom II. It is quite similar to the spiderdemon but smaller and with large eyes that change color depending on the monster's current state (moving, hurt, or attacking). It is supported by a metal chassis and his body consists primarily of a large brain, along with two small arms. Instead of a chaingun it wields a powerful plasma gun that fires bursts of yellow and green energy.

According to the manual: ''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.''

Combat characteristics
Once the arachnotron engages an enemy it will continue to fire until the enemy moves out of its field of view or until the monster flinches in pain or is destroyed. Similar behavior can be observed with the spiderdemon and the heavy weapon dude.

Tactical analysis
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. They have a medium pain chance, so rapid fire weapons will work well, although using the chainsaw on them is very risky. Their attacks are easier to avoid than the hitscan attacks of the other monsters that use rapid fire weapons, but the plasma bursts move faster than most other projectiles and can quickly hurt the player severely, if not avoided. If a player constantly attacks, moves in broad side-to-side movements, and tries to get out of the arachnotron's line of fire periodically, then the player will sustain minimal damage. Additionally, the projectiles fired by arachnotrons can obscure the player's vision.

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 arachnotron is first encountered on these maps:

The IWADs contain the following numbers of arachnotrons:

Doom 64
The Doom 64 arachnotron has 2 plasma guns. In addition its appearance is different: it is a bit higher, the legs have more mass, it has red eyes insted of blue and the brains are smaller and more pink in tone.

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

Arachnotrons attack three times consecutively, and are most weak against bullets and rockets.
 * Arachnotron (normal colors)
 * Plasmodium (light green brain, bronz-colored robotic chassis)
 * Astaroth (light purple brain, gold-colored robotic chassis)