Arcane glutton

Magic resistance.  The Arcane glutton has advantage on saving throws against spells and other magical effects.

Sturdy. The Arcane glutton has advantage on checks against being moved or knocked prone.

Arcane Sight. The Arcane glutton discerns the location of all magical auras within sight and knows which creatures within 60 feet are spellcasters.

Multi-attack. The Arcane glutton can make 1 with its bite and 1 with its tail. It can't make both attacks against the same target.

Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., 1 target. Hit: 11 (2d8 + 2) piercing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 17). Until this grapple ends, the target is restrained, and the Glutton can't bite another target. On its next turn, the Arcane glutton can swallow a creature in its mouth.

Stinger. Melee Weapon Attack: +6 to hit, reach 10 ft., 1 target. Hit: 8 (1d10 + 2) piercing damage. 

Magic inhale. The arcane glutton inhales in a 30ft cone all creatures in the area must make a DC10 strength saving throw or be pulled to an unoccupied space with 10ft of the arcane glutton. The DC increases for each magical item on their person (stacks of magic consumables count as 1 item)

Variant
When the Arcane glutton uses its consume spell ability it can forgo healing on its turn and force the spell caster to roll on the wild magic table.

Reactions. The Arcane glutton can make 2 reactions but only once per turn

Consume spell. When the Arcane glutton is targeted or forced to make a saving throw by a spell of 3rd level or lower it can use its reaction to consume the spell energy countering the spell. At the start of its next turn, the arcane glutton heals for 2d4 as long as it is not at 0 hit points. (recharge 5-6)

Absorb Elements. The Arcane glutton can grant itself resistance to the incoming energy of an attack (acid, cold, fire, lightning, or thunder). Also, the first time the Arcane glutton hits with a melee attack on its next turn, the target takes an extra 1d6 damage of the triggering type.