Thadoamoe
Singular
2d4 hit points, 0 Armor
Suffocate and Constrict (1d4 damage, +1/round)
Thadoamie run from one to two meters long and wide, averaging about two millimeters thick. They hold a small but surface-wide static charge and can cling flush to almost any reasonably flat surface. Their skin changes to take the coloration of any surface they are against, even for a few days after death. They secrete a digestive substance on volition which slowly melts animal flesh down to a digestible goo that the Thadoamoe can absorb through it’s “skin.”
They attack lone targets by dropping on them from ceilings or flinging themselves off walls and constricting against them, sometimes binding legs or arms but most often tightening chests or covering faces, suffocating their targets.
A thadoamoe will never attack a creature unless they think it is alone.
The only known sign that a thadoamoe might be near is a slow dripping sound when it thinks a meal is coming – the digestive juices increase and sometimes droplets fall away when it is anticipating a meal.
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Thadoamie don’t exist. They are a boogieman parents use to keep their children from going alone into dark or dangerous places. PCs born into the world will, of course, have heard these stories. Find an excuse to mention them while the party is in a civilized place (a mother scolding her filthy son for climbing into the sewer system, maybe)
If a member of the group ever has cause to leave the protection of the party mid-delve, play up the dripping that is ever present underground if you want to spotlight a moment of their character conquering their own sense of fear.