Arcanaphage

Medium Monstrosity unaligned

STR	DEX	CON	INT	WIS	CHA
10 (+0)	18 (+4)	16 (+3)	2 (-4)	10 (+0)	8 (-1)

Skills: perception +2
Damage Resistances: bludgeoning, piercing, and slashing from magical weapons
Condition Immunities: blinded, charmed, deafened, frightened, prone
Senses: blindsight 60 ft. (blind beyond this radius), passive Perception 12
Languages: -

Arcane Discharge: When an arcanaphage dies, it explodes in a surge of partially-digested magical energy. Each creature within 5 feet per Feed score must make a DC 14 Dexterity saving throw, taking 3 (1d6) force damage per Feed score on a failed save, or half as much damage on a successful one. For 1 minute afterward, the affected area is awash with volatile magic. A creature that starts its turn in the affected area takes 7 (2d6) force damage.
Hunger: Each time it feeds in combat, it regains hp equal to twice the level of the spell it ate and increases its Feed score by 1. The arcanaphage can't have a Feed score higher than 8, and its Feed score reduces by 1 each time it finishes a long rest.
Ingest Magic: At the start of each of the arcanaphage's turns, each creature within 30 feet of it that is currently maintaining concentration on a spell must make a DC 14 Constitution saving throw. On a failure, the creature's spell ends and the arcanaphage feeds.
Magic Immunity: The arcanaphage is immune to damage from spells. It has advantage on saving throws against all other magical effects.

Multiattack: The arcanaphage makes two tentacle attacks.
Tentacle: Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) bludgeoning damage.

Voracious: The arcanaphage's tentacles glow when a spell is cast within 30 feet of it, countering the spell. This reaction works like the counterspell spell, except the arcanaphage must always make a spellcasting ability check, no matter the spell level. Its ability check for this is +5. If it successfully counters the spell, the arcanaphage feeds.