Buzzek - Chosen of Zariel

Diabolical Restoration. If the pit fiend dies outside the Nine Hells, its body disappears in sulfurous smoke, and it gains a new body instantly, reviving with all its Hit Points somewhere in the Nine Hells.

Fear Aura. The pit fiend emanates an aura in a 20-foot Emanation while it doesn’t have the Incapacitated condition. Wisdom Saving Throw: DC 21, any enemy that starts its turn in the aura. Failure: The target has the Frightened condition until the start of its next turn. Success: The target is immune to this pit fiend’s aura for 24 hours.

Legendary Resistance (4/Day). If the pit fiend fails a saving throw, it can choose to succeed instead.

Magic Resistance. The pit fiend has Advantage on saving throws against spells and other magical effects.

Multiattack. The pit fiend makes one Bite attack, two Devilish Claw attacks, and one Fiery Mace attack. It can replace its uses of Devilish Claw with Chain of Avernus attacks.

Bite. Melee Attack Roll: +14, reach 10 ft. Hit: 18 (3d6 + 8) Piercing damage. If the target is a creature, it must make the following saving throw. Constitution Saving Throw: DC 21. Failure: The target has the Poisoned condition. While Poisoned, the target can’t regain Hit Points and takes 21 (6d6) Poison damage at the start of each of its turns, and it repeats the save at the end of each of its turns, ending the effect on itself on a success. After 1 minute, it succeeds automatically.

Chain of Avernus. Melee Attack Roll: +14, reach 30 ft. Hit: 18 (4d4 + 8) Force damage plus 14 (6d4) Fire damage. On a hit, the target is pulled 25 feet towards the Pit Fiend and must make the following saving throw: Strength Saving Throw: DC 21. Failure: The target has the grappled condition (The Pit Fiend can only have one target grappled in this way). While grappling a target in this way, the Pit Fiend can target another creature with a Chain of Avernus attack. On a hit, both the target and the grappled creature take the attack's damage, the grappled creature is released and falls Prone.

Devilish Claw. Melee Attack Roll: +14, reach 10 ft. Hit: 26 (4d8 + 8) Necrotic damage.

Fiery Mace. Melee Attack Roll: +14, reach 10 ft. Hit: 22 (4d6 + 8) Force damage plus 21 (6d6) Fire damage. The target is pushed 15ft away from the Pit Fiend and must make the following saving throw: Strength Saving Throw: DC 21. Failure: The target falls Prone.

Hellfire Spellcasting (Recharge 4–6). The pit fiend casts Fireball (level 5 version) twice, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 21). It can replace one Fireball with Hold Monster (level 7 version) or Wall of Fire.

Infernal Reinforcements. The Pit Fiend casts the Gate spell, targeting Avernus only. Once the spell has been cast in this way, it cannot be cast again until the Pit Fiend takes a long rest or successfully uses Archduke's Audience.

Archduke's Audience. When the Pit Fiend hits a creature, it can grant that creature an audience with Zariel, Archduke of Avernus. Charisma Saving Throw: DC 21. Failure: The creature disappears and hurtles through a nightmare landscape. The target takes 10d10 Psychic damage if it isn't a Fiend and it has the Incapacitated until the end of the Pit Fiend's next turn, when it returns to the space it previously occupied or the nearest unoccupied space. Once this ability has been used, it cannot be used again until the Pit Fiend takes a short or long rest.

Flank in Flame (7/Day). The Pit Fiend teleports itself or a willing ally within 10 feet up to 60 feet to an unoccupied space it can see. 

Vanguard's Thirst. The Pit Fiend lets out a ravenous war cry, spurring its fellow combatants within 60 feet. Until the start of its next turn, the Pit Fiend and its allies have advantage on attack rolls. Once this ability has been used it cannot be used again until the Pit Fiend takes a short or long rest or it reduces a creature to 0 Hit Points.

Fiendish Retaliation (7/day). Trigger: The Pit Fiend takes damage from a creature within 30 feet. Response: Dexterity Saving Throw: DC 21. Failure: The creature takes 3d10 Fire damage as flames erupt from the ground at its feet.