Arachnotron (Doom Eternal)

The arachnotron returns as a monster in Doom Eternal, its first appearance in a main-series Doom game since Doom 64, and in any Doom game since Doom II RPG. As with previous versions of the monster, it is a brain-like monster with small, frail arms, equipped with a mechanical chassis that walks on multiple clawed legs like an arachnid, essentially being a smaller version of the Spider Mastermind. Uniquely, this new incarnation carries its plasma gun on a -like tail which it holds above its body. Its legs are similar to the Doom 64 counterpart. Additionally, the arachnotron now has blue-colored blood akin to the cacodemon.

Tactical analysis
The arachnotron attacks using its plasma gun for continuous direct shots and the grenade launchers for lobbed area-of-effect shots. It is able to cling to walls and ceilings to stay out of reach, but attacking its legs in this state will cause it to lose its grip and fall. The arachnotron's turret can be destroyed due to the new destructible demons gore mechanic. If forced into close range or if its gun is destroyed, it attacks by swiping at the Doom Slayer with its leg claws or by firing grenades. Like the Spider Mastermind, the arachnotron can quickly dash sideways to avoid incoming fire.

Lore
After the defeat of the Spider Mastermind by the Doom Slayer, its remains were salvaged by UAC cultists and the resulting genetic material used to create a new breed of demon. While the arachnotron possesses limited mobility of its own, the arachnotron's well-developed brain is ideally suited for the prosthetic frame into which it is built.

An automated factory was set up to mass-produce the arachnotrons. As the first generation of arachnotrons slaughtered their own creators upon completion, the factory remains operational entirely under the direction of an artificial intelligence.

Glory kills

 * The Doom Slayer grabs one (or both, if from behind) of the arachnotron's arms and forces the claw through the monster's eye.
 * The Doom Slayer flips the arachnotron onto its back, where it is crushed by its own weight.
 * The Doom Slayer snatches a grenade from the launcher and feeds it to the arachnotron.
 * The Doom Slayer snatches a grenade from the launcher and jams it in the arachnotron's brain.

Pre-release
The arachnotron was confirmed to return in the game's original announcement at the BE3 presentation on. An arachnotron appeared in the background of the scene walking toward the location where the Doom Slayer is eventually shown.

The arachnotron first appeared in gameplay during a modified version of the Super Gore Nest level in the BE3 presentation as part of a cutscene. It implies that the arachnotron will make its first appearance there, but this is not the case for the final version of the game, whereupon it was introduced as early as Hell On Earth. The cutscene itself is not seen either.