Azorg

Legendary Resistance (6/Day). If Azorg fails a saving throw, he can choose to succeed instead.

Fear Aura. Any creature hostile to Azorg that starts its turn within 20 feet of him must make a DC 21 Wisdom saving throw, unless he is incapacitated. On a failed save, the creature is frightened until the start of its next turn. If a creature's saving throw is successful, the creature is immune to Azorg's Fear Aura for the next 24 hours.

Magic Resistance. Azorg has advantage on saving throws against spells and other magical effects.

Magic Weapons. The pit fiend's weapon attacks are magical.

Innate Spellcasting. Azorg's spellcasting ability is Charisma (spell save DC 21). The pit fiend can innately cast the following spells, requiring no material components:

At will: detect magic, fireball

3/day each: hold monster, wall of fire

Multiattack. Azorg makes four attacks: one with its bite, one with its claw, one with its mace, and one with its tail.

Bite. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 22 (4d6 + 8) piercing damage. The target must succeed on a DC 21 Constitution saving throw or become poisoned. While poisoned in this way, the target can't regain hit points, and it takes 21 (6d6) poison damage at the start of each of its turns. The poisoned target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Claw. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 17 (2d8 + 8) slashing damage.

Mace. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 15 (2d6 + 8) bludgeoning damage plus 21 (6d6) fire damage.

Tail. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 24 (3d10 + 8) bludgeoning damage.

Summon Devil (1/Day). Azorg summons 2d8 tiefling warriors, 2d4 bearded devils, 1d4 barbed devils or one erinyes. A summoned devil appears in an unoccupied space within 60 feet of its summoner, acts as an ally of its summoner and can't summon other devils. It remains for 1 minute, until it or its summoner dies, or until its summoner dismisses it as an action.

Azorg can take 6 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature's turn. Azorg regains spent legendary actions at the start of his turn.

Attack (Costs 2 Actions). Azorg makes one mace attack and one tail attack.

Breath Attack (Costs 4 Actions). Azorg opens his mouth and a 10 foot cone of fire comes out. Each creature within 10 feet of Azorg must succeed on a DC 23 Dexterity saving throw or take 16 (2d6 + 9) fire damage. Azorg can then move up to half his moving or flying speed.

Detect. Azorg makes a Wisdom (Perception) check.