Death Throes. When Aborzuhl dies, it explodes, and each creature within 30 feet of it must make a DC 20 Dexterity saving throw, taking 90 (20d8) fire 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 balor’s weapons.

Fire Aura. At the start of each of Aborzuhl's turns, each creature within 10 feet of tehm takes 14 (4d6) fire 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 10 feet of it takes 10 (3d6) fire damage.

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

Magic Weapons. Aborzuhl's weapon attacks are magical.

Formless Horror. Aborzuhl does not provoke attacks of oportunity.

Unstopable Fury. Aborzuhl ignores resistance against being frightened and treats immunity against fire as resistance against fire.

Multiattack. Aborzuhl makes 6 attacks: four with its Claws, one with its Gaze and one with its Breath.

Claws. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 28 (4d8 + 10) slashing damage plus 16 (4d8) fire damage. If Aborzuhl scores a critical hit, it rolls damage dice three times, instead of twice.

Gaze of burning Hatred. Ranged Weapon Attack: +14 to hit, reach 60 ft., one target. Hit: 19 (4d6 + 7) fire damage plus 10 (3d6) force damage, and the target must succeed on a DC 21 Wisdom savingthrow or be frightened until the begining of Aborzuhl's next turn.

Breath of  Blinding Fire [Recharge 4-6]. Aborzuhl exhales fire and smoke in a 20-foot radius around them. Each creature in that area, that isn't a spwan of Aborzuhl, must make a DC 21 Dexterity saving throw, taking 40 (12d6) fire damage and are blinded until the start of Aborzuhl's next turn on a failed save, or half as much damage on a successful one.

Flame Teleportation. Aborzuhl teleports to a space unoccupied by anything but a Spwan of  Hatred, that has some source of fire inside it, within 40ft. If Aborzuhl takes up the space of one or more Spawn's of Hatred they absorb them and get healed for the total amount of remaining hit points.

1 Legendary action. 2Claw attacks or 1 Gaze attack
2 Legendary actions. Breath of Division Aborzuhl breaths a dark smoke in a 15-foot cone forcing every creature, hostile to them, to make a DC22 Wisdom savingthrow.
On a failed save a creature must attack a creature other then Aborzuhl or a Spwan of Hatred  and they can't use defensive actions, as shield or the dodge action, until the end of their next turn. 
On a succesfull save a creature takes 6d4 psychic damage.