The glabrezu's spellcasting ability is Intelligence (spell save DC 16). The glabrezu can innately cast the following spells, requiring no material components:
At will: darkness, detect magic, dispel magic
1/day each: confusion, fly, power word stun
The glabrezu has advantage on saving throws against spells and other magical effects.
The glabrezu makes four attacks: two with its pincers and two with its fists. Alternatively, it makes two attacks with its pincers and casts one spell.
Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) bludgeoning damage. If the target is a Medium or smaller creature, it is grappled (escape DC 15). The glabrezu has two pincers, each of which can grapple only one target.
Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 7 (2d4 + 2) bludgeoning damage.