Armor Class 18 (natural armor)
Hit Points 337 (27d10 + 189)
Speed 40 ft., fly 40 ft.
Saving Throws DEX +8, CON +14, INT +15, WIS +14
Skills Deception +15, Perception +14, Stealth +8
Damage Resistances cold, fire, lightning
Damage Immunities poison, [object Object]
Condition Immunities charmed, exhaustion, frightened, poisoned
Senses truesight 120 ft., passive Perception 24
Languages all, telepathy 120 ft.
Challenge 23
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.
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.
Mordenkainen Presents: Monsters of the Multiverse, p. 129