Truant Devourer

Heretic Sense. Can pinpoint location of heretics of its faith within 60' of it and can sense their general direction within 1 mile of it.

Magic Resistance. Advantage: spell/magic effect saves.

Turn Resistance. Advantage: saves vs. turn undead effects.

Undead Nature. Doesn't require air food drink or sleep.

Multiattack. Three Devourer's Cleaver or Necrotic Bolt attacks. It can replace one attack with Life Drain attack.

Devourer's Cleaver. Melee Weapon Attack: +7 to hit, 5 ft., one target, 10 (2d6+3) slashing damage + 9 (2d8) necrotic.

Life Drain. Melee Spell Attack: +8 to hit, 5 ft., one creature,. 17 (3d8+4) necrotic. Target's hp max is reduced by amount equal to damage taken (DC 16 Con negates hp max). Reduction lasts until target finishes a long rest. Target dies if this reduces its hp max to 0.

Necrotic Bolt. Ranged Spell Attack: +8 to hit, 120 ft., one target, 17 (3d8+4) necrotic.

Invisibility. Magically turns invisible (with items worn/carried) until it attacks uses Grasping Claws or concentration ends (as a spell).

Grasping Claws (Recharge 5-6). Calls dozens of ghostly skeletal claws to erupt from a point on the ground it can see within 60' of it. All within 15 ft. of that point: 31 (7d8) necrotic and restrained 1 min (DC 16 Dex half damage not restrained). Restrained creature can re-save at end of each of its turns success ends effect on itself.

Dusty Step. Teleports with items worn/carried up to 60' to unoccupied space it can see. Dust cloud appears at origin and destination.