Spelldrinker

Medium undead, neutral evil
Armor Class 14 (natural armor)
Hit Points 52 (8d8 + 16)
Speed 30 ft.

STR	DEX	CON	INT	WIS	CHA
16 (+3)	14 (+2)	15 (+2)	11 (+0)	8 (–1)	13 (+1)

Saving Throws Dex +4
Skills Perception +1, Stealth +4
Damage Resistances bludgeoning, piercing, and slashing from nonmagical weapons
Senses darkvision 60 ft., passive Perception 11
Languages the languages it knew in life
Challenge 3 (700 XP)

Magic Resistance. The spelldrinker has advantage on saving throws against spells and other magical effects.

Sunlight Sensitivity. While in sunlight, the spelldrinker has disadvantage on attack rolls, as well as on Wisdom (Perception) checks that rely on sight.

Spider Climb. The spelldrinker can climb difficult surfaces, including upside down on ceilings, without needing to make an ability check.

Actions

Multiattack. The spelldrinker makes two attacks, only one of which can be a bite attack.

Claws. Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (2d4 + 3) slashing damage. If the target is a Medium or smaller creature, the spelldrinker can choose to grapple it (escape DC 13) instead of dealing damage.

Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one willing creature or one creature that has been grappled by the spelldrinker, is incapacitated, or is restrained. Hit: 6 (1d6 + 3) piercing damage plus 7 (2d6) necrotic damage. If the target is a spellcaster, it loses one spell slot of its highest level. The spelldrinker regains hit points equal to 5 × the level of the spell slot consumed. If the target has no spell slots or has no spell slots remaining, it takes an additional 14 (4d6) necrotic damage. If this damage reduces the creature to 0 hit points, it dies.

If a creature killed in this way can cast spells, its corpse transforms into a spelldrinker in 1d4 days unless cured by a remove curse spell or similar magic. If the creature cannot cast spells, it instead becomes a ghoul in 1d4 days.