Molydeus

Huge fiend (demon), chaotic evil
Armor Class 19 (natural armor)
Hit Points 216 (16d12 + 112)
Speed 40 ft.
STR
28 (+9)
DEX
22 (+6)
CON
25 (+7)
INT
21 (+5)
WIS
24 (+7)
CHA
24 (+7)
Saving Throws Str +16, Con +14, Wis +14, Cha +14
Skills Perception +21
Damage Resistances cold, fire, lightning; bludgeoning, piercing, and slashing from nonmagical attacks
Damage Immunities poison
Condition Immunities blinded, charmed, deafened, frightened, poisoned, stunned
Senses truesight 120 ft., passive Perception 31
Languages Abyssal, telepathy 120 ft.
Challenge 21 (33000 XP)
Innate Spellcasting.
Legendary Resistance (3/Day).
Magic Resistance.
Magic Weapons.
ACTIONS
Multiattack.
Demonic Weapon.
Wolf Bite.
Snakebite.
LEGENDARY ACTIONS
Attack.
Move.
Cast a Spell.

This full creature's stat block is not available (not OGL).

Mordenkainen´s Tome of Foes
Molydeus