Adaptive Aura. At the start of each of the empyrean's turns, each creature within 5 feet of it takes 10 (3d6) damage of one of the following types (empyrean’s choice): acid, cold, fire, force, lightning, radiant, or thunder damage and flammable objects in the aura that aren’t being worn or carried ignite. A creature that touches the balor or hits it with a melee attack while within 5 feet of it takes 10 (3d6) damage of one of the following types (empyrean’s choice): acid, cold, fire, force, lightning, radiant, or thunder damage.

Dominative Might. (Mythic Trait; Recharges after a Short or Long Rest). If the empyrean is reduced to 0 hit points, it doesn't die or fall unconscious. Instead, it regains 300 hit points. In addition, the empyrean gains three additional attacks on its turn.

Death Throes. When the empyrean dies, it explodes, and each creature within 30 feet of it must make a DC 20 Dexterity saving throw, taking 70 (20d6) damage of the following types (empyrean’s choice): acid, cold, fire, force, lightning, radiant, or thunder damage on a failed save, or half as much damage on a successful one. The explosion ignites flammable objects in that area that aren’t being worn or carried, and it destroys the empyrean's weapons.

Innate Spellcasting. The empyrean’s innate spellcasting ability is Charisma (spell save DC 24, +16 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: pulse wave, hold person, dispel magic, lightning bolt, fireball

1/day each: dominate monster, dark star, reality break, fire storm, plane shift (self only)

Legendary Resistance (3/Day). If the empyrean fails a saving throw, it can choose to succeed instead.

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

Magic Weapons. The empyrean’s attacks are magical.

Three Heads. The empyrean has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Multiattack. The empyrean makes three attacks any of its attacks.

Fist of Havoc. Melee Weapon Attack: +18 to hit, reach 10 ft., one target. Hit: 31 (6d6 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 15 Constitution saving throw or be stunned until the end of the empyrean’s next turn.

Bolt of Sundering. Ranged Spell Attack: +16 to hit, range 600 ft., one target. Hit: 24 (7d6) damage of one of the following types (empyrean’s choice): acid, cold, fire, force, lightning, radiant, or thunder.

Chain Whip. Melee Weapon Attack: +18 to hit, reach 30 ft., one target. Hit: 15 (2d6 + 8) slashing damage plus 10 (3d6) damage of one of the following types (empyrean’s choice): acid, cold, fire, force, lightning, radiant, or thunder damage, and the target must succeed on a DC 20 Strength saving throw or be pulled up to 25 feet toward the empyrean.

The empyrean can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The empyrean regains spent legendary actions at the start of its turn.

Attack. The empyrean makes one attack.

Move. The empyrean moves up to half its speed.

Cast At Will Spell.  The empyrean cast one at will spell.

Cast Once a Day Spell (Cast 2 Actions). The empyrean cast one once a day spell.

Trembling Strike (Costs 2 Actions). The empyrean strikes the ground with its all its might, triggering an earth tremor. All other creatures on the ground within 60 feet of the empyrean must succeed on a DC 25 Strength saving throw or be knocked prone.

If empyrean's mythic trait is active, it can use the options below as legendary actions for 1 hour after using Dominative Might.

Martial Defense. The empyrean takes the dodge action.

Inspire Terror (Cost 2 Actions).  The empyrean curses all hostile creatures within a 120 feet. Each creature must succeed on a DC 22 wisdom save or be cursed, having disadvantage on ability checks and saving throws until the end of the empyrean’s next turn.