Apocalypse, Angel of the Abyss

Demonic Weapons. Apocalypse's weapon attacks are magical. When he hits with any weapon, the weapon deals an extra 45 (10d8) necrotic damage (included in the weapon attacks below).

Death Throes: When Apocalypse dies, he explodes, and each creature within 30 feet of it must make a DC 21 Dexterity saving throw, taking 70 (20d6) 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 Abbadon's weapons.

Fire Aura: At the start of each of Apocalypse's turns, each creature within 5 feet of it takes 10 (3d6) fire damage, and flammable objects in the aura that aren't being worn or carried ignite. A creature that touches Apocalypse or hits it with a melee attack while within 5 feet of it takes 10 (3d6) fire damage.

Innate Spellcasting. Apocalypse's innate spellcasting ability is Charisma (spell save DC 26). He can innately cast the following spells, requiring no material components.

At will: alter self (can become medium when changing his appearance), detect evil and good, major image, invisibility, nondetection

3/day each: blade barrier, disintegrate, dispel evil and good

1/day: control weather, dominate monster, power word kill

Legendary Resistance (3/Day). Apocalypse fails a saving throw, he can choose to succeed instead.

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

Regeneration. Apocalypse regains 30 hit points at the beginning of his turn. If he takes radiant damage, this trait doesn't function until the start of his next turn.

Multiattack. Apocalypse attacks twice with his Demonic Greatsword or with his Corrupting Longbow. He can substitute Conflicting Pain for one of these attacks.

Demonic Greatsword. Melee Weapon Attack: +18 to hit, reach 5 ft., 1 target. Hit: 26 (4d8 + 10) slashing damage 45 (10d10) necrotic damage.

Corrupting Longbow. Ranged Weapon Attack: +15 to hit, reach 150/600 ft., 1 target. Hit:  (2d8 + 7) piercing damage 45 (10d10 necrotic damage).

Conflicting Pain (Recharge 5-6). Apocalypse chooses a creature he can see within 120 feet of him. The creature must make a DC 25 Constitution saving throw or take 55 (10d10) poison damage, and the target is poisoned for 1 minute. While poisoned in this way, the target is also blinded and deafened. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Summon Demon (1/Day). Refer to Monster Manual page 55.

Teleport. Apocalypse magically teleports, along with any equipment he is wearing and carrying, up to 120 feet to an unoccupied space he can see.

Apocalypse 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. Apocalypse regains spent legendary actions at the start of his turn.

Teleport. Apocalypse uses his teleport action.

Weapon Attack. Apocalypse may make one attack with his greatsword or bow.

Gaze of Destruction (2 actions). A creature that Apocalypse sees within 120 feet of him, must make a DC 26 Constitution saving throw or take 30 (6d10) force damage. If the creature dies, they are disintegrated and only may be brought back through the means of true resurrection or a wish spell.