Crypt Thing, Aberrant (5e Creature)
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Medium undead, neutral evil
Skills History, Perception, Stealth
Crypt Dance. While within 30 feet of the crypt thing, any undead ally of the crypt thing may use a bonus action on their turn to move 10 feet.
Multiattack. The crypt thing makes two rake attacks.
Rake. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: X (1d8 + 3) slashing damage plus 7 (2d6) necrotic damage. If the target is a creature other than an elf or undead, it must succeed on a DC 16 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
Vanishing Trick (Recharge 6). The crypt thing targets one creature it can see within 60 feet of it. The target must make a DC 16 Constitution saving throw. On a failed save, the target becomes blinded, deafened, paralyzed and invisible for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
The can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The regains spent legendary actions at the start of its turn.
A pale, solitary skeletal being wearing a brown hooded cloak, the crypt thing remains permanently in its lair. It will not attack if left undisturbed. Its aim appears to be soley that of obtaining pleasure by creating confusion and dissent.
When adventurers first intrude into the aberrant crypt thing's lair, it will match their demeanor (although never so friendly as to be suspicious). It will ask the intruders to leave its crypt. If the intruders persist, the crypt thing will use vanishing trick on the target that seems least able to resist (the party wizard, perhaps) and declare that it has disintegrated this victim. Again, it will encourage the intruders to leave. If the party calls its bluff, it will attack with its claws, continuing to use vanishing trick as it recharges.
Victims who have been "vanished" are unable to communicate their situation, and the DM may even make their saving throws in secret. Another character accidentally bumping into the victim may give a big clue; attempts to aid the victim will be at the usual penalty for an invisible target.