Truant Devourer

Armor Class: 16
Hit Points: 156 (24d8+48)
Speed: walk 40 ft.
Challenge Rating: 9 (5,000 XP)
Source: Tome of Beasts 3, page 378

Medium Undead any alignment (as its creator deity)

STR	DEX	CON	INT	WIS	CHA
12 (+1)	17 (+3)	14 (+2)	16 (+3)	18 (+4)	13 (+1)

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.