Arcanius Devourer

Abjuring Hide. The Arcanius Devourer takes half damage from magical attacks from uncommon magical items and spells up to 3rd level spells, and is immune to spell effects below 3rd level. 

Arcane Tracker. The Arcanius Devourer has advantage on perception smell and survival checks made to track down arcane items, and spells like invisibility or pass without trace. 

MultiAttack. The Arcanius Devourer makes two attacks one with its void rend and another with its tail. or it can choose to use void burst.

Tail. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 14 (2d6+4) force damage.

Void Rend. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 5 (1d10+4) piercing damage. plus 7 (2d6) force damage.

Void Burst (Recharge 6 or targeted by a concentration spell). The Arcanius absorbs spells and magical energy within a 30 ft radius of itself. spells of 3rd level and below are absorbed as a part of this and are dispelled in a magical pulse wave of forceful energy. each creature within range of the Arcanius must make a DC 14 Constitution saving throw, on a failure a creature concentrating on a spell if they fail the saving throw has that spell concentration lost and be dealt 17 (4d8) force damage. for each spell absorbed by void burst, you deal an extra 1d8 per spell level. on a successful save a creature takes half damage, and can make a normal concentration check.