I finally dug my 3.5 monster manual out of the box so I'll probably talk about monster's 3.5 incarnation if my chosen monster appears in both.
3HD monsters with an armored head, soft body, and 8 paralytic attacks per turn. While modern interpretations tend to have caveats like
No matter how many of a tentacle worm's attacks hit an opponent in a given round, only one saving throw is required in each such round (BFRPG)
The AD&D manual doubles down and just says "As there are so many tentacles with which to hit, and thus multiple chances of being paralyzed, these monsters are greatly feared." Just a flat acknowledgement of 'yeah your players SHOULD be scared.' Given that they also show up in groups of 1d6, this is the sort of creature that really emphasizes how combat was not meant to be a honorable affair of standing face to face trading blows until one party was defeated and showing off your cool combat maths.
They've got Treasure Type B, which is potentially pretty good, but also unreliable, which makes sense- maybe they've dragged a bunch of gold-ring wearing nobles down to their lair, maybe they've just been eating giant rats.
The 3.5 Carrion Crawler is similarly deadly at first glance, but closer indication reveals that the paralysis DC is 13, which is pretty pitiful, and the duration of paralysis is a mere 2d4 rounds (no mention of duration is given in AD&D). Of some interest is the notes on behavior- the AD&D version mentions they are scavengers that will happily turn predatory to make corpses to either eat or lay their eggs in, the 3.5 version differs with them immediately turning to devour the paralyzed with their feeble, inaccurate bite, and that 'multiple crawlers do not fight in concert,but each paralyzes as many opponents as possible. The unintelligent creature continues to attack as long as it faces any moving opponents."
Them only attacking you if you move is good monster stuff, though the direction given in the more modern bestiary is clearly more tactically than strategically focused, given the lack of mention of egg-laying or scavenger preference.
Sunset Realm Sewer Snatchers
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| "I'm glad toilet paper hasn't been invented yet or I'd have some comedically stuck to my foot right about now"-This Guy |
Nasty, soft-bodied but segmented worm-creatures that love filth. Their tentacles are internal until such time as they inflate them with air and spew them forth like a bunch of slimy balloons, either as a threat display, or in preparation for attacking. The inflated tentacles have little real strength behind them despite their prodigious size, and is only the slimy, sticky, paralytic goop that is dangerous. Each tentacle has a simple heat-sensitive black eye that allows the tentacles to seek out warm flesh, and similar to an octopus, the tentacles operate semi-independently of the main brain. They do not have teeth, and live by slurping up the decaying juices of corpses. In breeding season, they capture and swallow live prey whole, though this is a slow, python like process. Due to their fairly aerated bowels (air being conserved inside the body to inflate tentacles) swallowed prey typically do not suffocate and are brought back to the lair alive, and are encased in a cement-like excretion while paralyzed. Eggs hatch when warmth draws near, releasing face-hugger like larvae which are weak but still sometime capable of paralyzing targets without the help of adults to bring them prey (1Hd, 1 attack that paralyzes only for 1d6 minutes, and thanks to Lungfungus for this inspiring take on carrion crawlers as Aliens) which then slither inside paralyzed prey, emerging (and killing the host) in 1d3+1 days as matured monstrosities. They can develop inside corpses as well, provided the corpse is intact enough to keep the pupating larvae safe from the external environment. The adults typically do not need to eat captured prey themselves, being able to survive off of scavenging garbage, and often use the prey-encasing secretions to 'wall off' areas of the dungeon to make the place more habitable
(tl;dr I want rescue to be an option rather than just 'lol tpk' if everyone is paralyzed and for them to change the dungeon if they're rolled as a restocking result, cuz they're a pretty good restocking result- eating the corpses of the dead, and incidentally guarding their treasures. Add in some ability to wall off passages and you've got a good way to freshen up old areas)
And it is garbage they scavenge, for they are attracted to waste-producing civilizations, and many a horror story features them emerging from the outhouse of a peasant or a noble's privy, depending on the audience. Ratcatcher Guilds (like park rangers and the town guard, but for the sewers) tend to keep these creatures in check with a standard 'Squid Squad' of a few men with long pikes, and a few more with crossbows, and enjoy occasional accolades for rescuing someone from the lair of an established nest. As they are not particularly intelligent, they are sometimes captured in cage traps and kept in dungeons of mad barons and so on, as, while untrainable, they make for good incidental guard monsters that will capture, rather than kill, interlopers, and can clean up garbage besides. This is, of course, highly illegal, as these beings are greatly reviled by humans, not so much for the danger, but for the potential body-horror.
Despite their love for sewer systems, they are actually creatures of the deep earth, and can be found in any subterranean location that connects to the deep roads and caverns of the veins of the earth. The sun bewilders them and they are effectively blinded by it, but it does not actually harm them. They are also decently amphibious, and in addition to swimming through sewer gunk, they can occasionally be found in tide pools, coastal caverns, or stuck to the underside of particularly foul piers, and there are occasional tall tales of them stowing away on ships and slowly picking off crew members, though this is dubious at best. A common factor is always moisture and rot through- in frigid regions where corpses freeze, and dry regions where corpses desiccate rather than go juicy, one cannot expect to find these beasts.
A quick note on Horror vs Mundanity
Explaining something makes it less scary, but also opens the possibility of having interactions that aren't just the players screeching, throwing molotovs everywhere, and fleeing into the night. I decided to normalize these monsters within the setting because hey, they're a classic monster, and trying to be too coy about that sort of thing can be a bit eye-rolling for everyone involved, as can over hyping something that honestly is no match for a handful of normal humans with half a brain and someone equipping them. Carrion crawlers are, I think, better suited for the naturalistic dungeons where monsters have ecology and there's a bathroom the bugbears use, rather than trying to be a mythic, symbolic monster that can't be handled by a half-dozen yahoos from the Ratcatcher's guild.
