Aspect of Alphariox, Dragon Forebearer

Draconic Perfection. If the aspect would be reduced to 0 hit points, her current hit point total instead resets to 500, she Recharges her breath weapon, and she regains any expended uses of her Legendary Resistance. In addition, the aspect can now use the options in the "Mythic Actions" section for 1 hour. Award a party an additional 155,000 XP (310,000 XP Total) for defeating the Aspect of Alphariox after her Draconic Perfection trait activates.

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

Multiattack. The aspect makes three attacks: one with her bite, one with her claws, and one with her tail

Bite. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 23 (2d12 + 10) piercing damage plus 22 (4d10) radiant damage.

Claw. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) slashing damage. If the Target is a Huge or smaller creature, it is grappled (escape DC 20) and is restrained until this grapple ends. The aspect can have only one creature grappled in this way at a time. 

Tail. Melee Weapon Attack: +19 to hit, reach 20 ft. cone. Hit: 23 (2d12 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.

Progenitor's Breath - Cone (Recharge 5–6). The aspect exhales a multicolored display, refracting from the aspects mouth outwards in a 150-foot cone. Each creature in that area must make a DC 26 Dexterity saving throw, taking 44 (8d10) radiant damage, and 5 (1d10) damage each of Fire, Lightning, Cold, Poison, and Acid on a failed save, or half as much damage on a successful one. This damage bypasses resistance, and reduces immunity to these damages to resistance instead. This breath attack shares a recharge with the Progenitor's Breath - Line breath attack.

Progenitor's Breath - Line (Recharge 5–6). The aspect exhales a multicolored display, refracting from the aspects mouth outwards in a 300-foot-line, 10 feet on each side. Each creature in that area must make a DC 26 Dexterity saving throw, taking 55 (10d10) radiant damage, and 11 (2d10) damage each of Fire, Lightning, Cold, Poison, and Acid on a failed save, or half as much on a successful one. This damage bypasses resistance, and reduces immunity to these damages to resistance instead. This breath attack shares a recharge with the Progenitor's Breath - Cone breath attack.

Celestial Indignance. If the aspect takes damage from another creature, she may make one Bite attack against that creature if they are within range.

The aspect 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 dragon regains spent legendary actions at the start of its turn.

Attack. The aspect makes one claw or tail attack.

Celestial Brilliance (Costs 2 Actions). The aspect lifts its body upright and channels energy into its golden halo. Each creature within 60 feet of the aspect must succeed on a DC 26 Constitution saving throw or be blinded and deafened until the end of their next turn.

If the aspects Draconic Perfection trait is active, she can use the options below as legendary actions.

Maelstrom of Creation (Costs 3 Actions). The Aspect flies up to half her speed and unleashes the energy of creation used to birth the first dragons. Choose 5 points within 120 feet. Each creature in a 20-foot-radius, 100-foot-high cylinder centered on each point must succeed on a DC 27 Dexterity saving throw or take 24 (7d6) Fire, Lightning, Cold, Poison, or Acid damage, choosing one for each of the points. A creature in the area of more than one cylinder is affected only once.