Aurelion Sol, The Star Forger

Center of the Universe. Aurelion Sol is constantly orbited by three Stars, each doing a full circumference on initiative count 20, and 20 ft. beyond them exists an Outer Limit affecting his damaging abilities. A creature in the path of a star must succeed a DC 24 Dexterity saving throw, taking 30 (5d10) radiant damage on a failure or half as much on a success.

Titanic Nature. Aurelion Sol doesn't require food or water to survive though he still needs to sleep.

Flyby. Aurelion Sol doesn’t provoke opportunity attacks when he flies out of an enemy’s reach.

Magic Weapons. Aurelion Sol’s weapon attacks are magical.

Siege Monster. Aurelion Sol deals double damage to objects and structures.

Legendary Resistance (4/Long Rest). If Aurelion Sol fails a saving throw, he can choose to succeed instead.

Rekindle a Dying Star (Mythic Trait; Recharges after a Short or Long Rest). If Aurelion Sol is reduced to 0 hit points, he doesn’t die or fall unconscious. Instead, he bursts with dazzling light, regains 299 hit points, and moves up to his speed without provoking opportunity attacks.

Multiattack. Aurelion Sol can use his Frightful Presence. He then makes three attacks: one with his bite and two with his claws.

Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) piercing damage plus 20 (6d6) radiant damage.

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 21 (3d6 + 10) slashing damage.

Tail. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 19 (2d8 + 10) bludgeoning damage.

Frightful Presence. Each creature of Aurelion Sol's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 21 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 Aurelion Sol's Frightful Presence for the next 24 hours.

Starsurge (Recharge 5-6). Aurelion Sol fires the core of a newborn star in a line, which expands as long as it remains within the Outer Limit. The star begins as a 10 ft. radius sphere of light and stardust expands from it growing 10 ft. larger for every 20 ft. Aurelion Sol travels. The star moves 5 ft. faster than Aurelion Sol, moves on his turn and detonates if he uses his action on Starsurge again or the core reaches the Outer Limit. Creatures within the area of effect must succeed a DC 21 Constitution saving throw, a creature struck by the core has disadvantage on this save. Creatures take 45 (10d8) radiant damage and is stunned until the end of Aurelion Sol's next turn on a failure. On a success creatures take half damage and are not stunned.

Celestial Expansion (Recharge 6). Aurelion Sol moves his orbiting Stars to his Outer Limit and doubles their orbiting speed until he takes damage, at which point they retract.

Comet of Legend (Recharge 8). As a bonus action, Aurelion Sol dashes and becomes immune to effects that would hinder his movement until the start of his next turn.

Voice of Light (Recharge 5–6). Aurelion Sol exhales starfire in a 90-foot line that is 10 ft. wide. Each creature in that area must make a DC 24 Constitution saving throw, taking 120 (30d6) radiant damage on a failed save, or half as much damage on a successful one.

Aurelion Sol can take 4 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. Aurelion Sol regains spent legendary actions at the start of his turn.

Detect. Aurelion Sol makes a Perception check.

Tail Attack. Aurelion Sol makes a tail attack.

Move. Aurelion Sol moves up to his speed.

Nova (Costs 2 Actions). Aurelion Sol recharges and uses Starsurge.

If Aurelion Sol’s mythic trait is active, it can use the options below as legendary actions for 1 hour after using Rekindle a Dying Star.

Outrage. Aurelion Sol make 2 attacks: 1 with his bite and 1 with his claws.

Breath of Creation (Costs 3 Actions). Aurelion Sol recharges and uses Voice of Light.