Legendary Resistance (3/Day). If Fraz-Urb'luu fails a saving throw, he can choose to succeed instead.

Magic Resistance. Fraz-Urb'luu has advantage on saving throws against spells and other magical effects.

Undetectable. Fraz-Urb'luu can't be targeted by divination magic, perceived through magical scrying sensors, or detected by abilities that sense demons or Fiends.

Spellcasting. Fraz-Urb'luu casts one of the following spells, requiring no material components and using Charisma as the spellcasting ability (spell save DC 23):

At will: alter self (can become Medium when changing his appearance), detect magic, dispel magic, phantasmal force

1/day each: modify memory, project image

3/day each: mislead, programmed illusion, seeming

Multiattack. Fraz-Urb'luu makes one Bite attack and two Fist attacks, and he uses Phantasmal Terror.

Bite. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit:19 (3d6 + 9) force damage.

Fist. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit:22 (3d8 + 9) force damage.

Phantasmal Terror. Fraz-Urb'luu targets one creature he can see within 120 feet of him. The target must succeed on a DC 23 Wisdom saving throw, or it takes 16 (3d10) psychic damage and is frightened of Fraz-Urb'luu until the end of its next turn.

Tail. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit:20 (2d10 + 9) force damage. If the target is a Large or smaller creature, it is also grappled (escape DC 24), and it is restrained until the grapple ends. Fraz-Urb'luu can grapple only one creature with his tail at a time.

Terror (Costs 2 Actions). Fraz-Urb'luu uses Phantasmal Terror.