Bahamut (Human Form)

Platinum Brilliance. (Recharges after a Short or Long Rest). If the aspect would be reduced to 0 hit points, his current hit point total instead resets to 350 hit points, he recharges his Breath Weapon, and he regains any expended uses of Legendary Resistance. Additionally, 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 Bahamut after his Platinum Brilliance activates.

Legendary Resistance (5/Day). If the aspect fails a saving throw, he can choose to succeed instead. 

Multiattack. The aspect makes three Longsword attacks, and two dagger attacks.

Longsword Attack. Melee Weapon Attack +17 to hit, reach 5 ft., one target. Hit 22 (2d12 +10) Slashing damage.

Dagger. Melee Weapon Attack + 13 to hit, reach 5 ft., one target. Hit 18 (3d8+6) Piercing damage.

Crossbow. Ranged Weapon Attack + 18 to hit, reach 40 ft,. one target. Hit 21 (2d10 + 10) piercing damage.

Breath Weapon (Recharge 5-6). The aspect uses one of the following Breath Weapons. 

Exalting Breath. The aspect exhales the restoring winds of Mount Celestia in a 300-foot cone. Each creature in that area of the aspect's choice regains 71 (13d10) hit points, and each creature in that area of the aspect's choice that has been dead for no longer than 1 hour is restored to life will all its hit points.

Platinum Breath. The aspect exhales radiant platinum flames in a 300-foot cone. Each creature in that area must make a DC 26 Dexterity saving throw, taking 66 (12d10) radiant damage on a failed save, or half as much damage on a successful one.

Change Shape. The aspect magically transforms into an Beast, or a Platinum Greatwyrm while retaining his in game statistics (other than his size). This transformation ends if the aspect is reduced to 0 hit points or if he uses a bonus action to end it. 

Platinum Brilliance (Recharges after a Short or Long Rest). If the aspect would be reduced to 0 hit points, his current hit point total instead resets to 350 hit points, he recharges his Breath Weapon, and he regains any expended uses of Legendary Resistance. Additionally, 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 Bahamut after his Platinum Brilliance activates.

Attack. The aspect makes one Longsword or Dagger attack.

Flurry of Swings (Costs 2 Actions). The Aspect makes one Longsword attack. If the attack hits a creature, the creature is hit by another 4 Longsword attacks automatically and must succeed on a DC 27 Wisdom saving throw or become frightened of the aspect until the end of the target's next turn.

If the aspect's Platinum Brilliance trait has activated in the last hour, he can use the options below as legendary actions.

Celestial Shield (Costs 2 Actions). The aspect manifests seven spectral ancient gold dragons around himself that protect him; he gains 77 temporary hit points until the start of his next turn.

Celestial Lances (Costs 3 Actions). The aspect conjures four enormous lances of magical force that plummet to the ground at four different points he can see within 150 feet of him and then disappear. Each creature in a 20-foot-radius, 100-foot-high cylinder centered on each point much succeed on a DC 27 Dexterity saving throw or take 24 (7d6) force damage. A creature in the area of more than one lance is affected only once.