Glabrezu

If the monster dies outside the Abyss, its body dissolves into ichor, and it gains a new body instantly, reviving with all its Hit Points somewhere in the Abyss.

The monster has Advantage on saving throws against spells and other magical effects.

The monster makes two attacks and uses or .

. . If the target is a Medium or smaller creature, it has the Grappled condition (escape DC ) from one of two pincers.

Dexterity Saving Throw: DC , one creature Grappled by the monster.
Failure: damage.
Success: Half damage.

The monster casts one of the following spells, requiring no Material components and using Intelligence as the spellcasting ability (spell save DC ):
At Will: Darkness, Detect Magic, Dispel Magic
1/Day Each: Confusion, Fly, Power Word Stun