The Krakaren's self-cloned young — rice-sized parasites that swell into acid-blooded octopus-monsters and, at floor's end, flood every station in a self-destruct swarm.
The Krakaren's self-cloned young grow from rice-sized Crotch Dumplings into swarming Krakaren Juvenile Clonelings — first monkey-sized (level 14-17), then dog-sized, then human-sized and seven feet tall (level 20-23). Covered in burning tentacles with round garbage-disposal mouths and screaming voices, their blood is caustic acid like the xenomorphs from Alien. Testing reveals they resist most attacks — fire and center-mass crossbow bolts work, psychic attacks freeze them, but lightning, freeze (unless an icicle through the body), and bashing (unless very hard) mostly fail.
They mass at the station 24s, filling the hidden tunnels between the mirrored 'noodle' tracks. When the floor initiates self-destruct, these hatches all open and the swarm 'spooges' up through the floors of every stairwell station — the political cartoon's exclamation point. Carl funnels thousands into the abyss with his portal-crane; where they die, they spawn fresh ghouls, making them monsters the crawlers must kill twice or three times over.
Octopus-like monsters ranging from rice-sized parasites to seven-foot beasts, covered in burning tentacles, with round teeth-filled garbage-disposal mouths and caustic, acidic blood.
The Krakaren swarm-young and the floor's self-destruct endgame weapon.
Also appears in books you've already read — spoiler-safe to their endings: