Amodeus

Discorporation. When Asmodeus drops to 0 hit points or dies, his body is destroyed but his essence travels back to his domain in the Nine Hells, and he is unable to take physical form for a time. 

Innate Spellcasting (3/Day each) Asmodeus can innately cast Divine word, Alter Self, Antimagic Field, Banishing Smite, Bestow Curse, Dominate person, Geas, Imprisonment, Incendiary Cloud, Prismatic Wall & Forbiddance.(Spell save DC 25) His spellcasting ability is Charisma.

Legendary Resistance (5/Day) If Asmodeus fails a saving throw, he can choose to succeed instead. Limited Magic Immunity Unless he wishes to be affected, Asmodeus is immune to spells of 6th level or lower. He has advantage on saving throws against all other spells and magical effects.

Regeneration. Asmodeus regains 35 hit points at the start of his turn.

Magic Weapons. Asmodeus's weapon attacks are magical.

Multiattack. Asmodeus can use his frightful presence. He then makes two attacks with his scepter.

Ruby Rod. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 42 (7d8 + 7 ) piercing damage.

Ranged Weapon Attack: +14 to hit, 150/600 ft., one target. Hit: 40 (5d12 + 5) fire damage.

It has has the ability to unleash the dragon fire of the great wrym Black (15 ft. line & 5 ft. area, DC 11 Dex Save, 5d8 acid dmg on fail or half dmg on save), Blue (30 ft. line & 5 ft. area, DC 12 Dex save,4d10 lightning dmg on fail or half dmg on save), and White (15 ft. cone, DC 12 Con save, 5d8 cold dmg on fail or half on save) types each can be cast five/day.

Frightful Presence. Each creature of Asmodeus’s choice that is within 240 feet of Asmodeus and aware of him must succeed on a DC 26 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to Asmodeus's Frightful Presence for the next 24 hours.

Soul Bartering. Asmodeus can grant any humanoid one wish (using the spell wish) in its lifetime on the condition that the PC is bound to him after death. Asmodeus can make minor changes to the wishes if he wants.

Now you see me. As a bonus action on his turn Asmodeus can teleport anywhere within his line of sight or in the nine hells.

LEGENDARY ACTIONS

The Asmodeus can take 5 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 Asmodeus regains spent legendary actions at the start of its turn. Chilling Gaze (Costs 1 Action). Asmodeus target one creature within 30 ft., the target makes a Constitution Save of DC 25 on a failed save target takes 2d10 psychic damage, target becomes frightened and gains 1 level of exhaustion.On gaining six levels of exhaustion creature doesn’t die but is dominated by Asmodeus.

Hell's Gate (Costs 2 Actions). As the King of Hell, Asmodeus has absolute control over all of the gates and portals that lead to Hell, as well as those within Hell. The Lord of the Nine can cause a gate or portal to open, sucking in those within 60 feet into a location in the Nine Hells of Asmodeus' choosing if they fail a Wisdom Save DC 25. The Mouth remains open for 3 rounds. A Hell's Mouth appears as a great, diabolically evil human male face with jagged, chewing teeth. Flames burst from the gaping maw as it attempts to suck in unlucky victims. The gate is two way and remains open for five rounds (suction only during first round).

Call of the Lord (Costs 2 actions). Asmodeus can summon three creatures (with a challenge rating of 5 or below) who resides within 9 hells.

Hell on Earth (Costs 1 action). Asmodeus can cause the surrounding area of 90 ft. to turn into that of Hell any creature that enters or is in the area makes a constitution saving throw of DC 25 on fail they take 5d8 fire dmg for each round they are inside the area on success they take half the damage. The creatures must continuosly make saving throws as long as they are within the area.

Contract established (Costs 1 action). Asmodeus on touching a humanoid or a piece of dead humanoid calls its soul back and forms a new adult body for the soul to enter. If the target isn’t willing to do so the spell fails. The body that is formed for the soul is a Tiefling’s body. The soul retains all it’s memories and experiences and is friendly towards Asmodeus (his memories are altered such that it obeys Asmodeus).