Celestial Dragon

Exalted Restoration. If the Celestial Dragon dies outside the Astral Plane, its body disappears, and it gains a new body instantly, reviving with all its Hit Points somewhere in the Astral Plane.

Magic Resistance. The Celestial Dragon has Advantage on saving throws against spells and other magical effects.

Amphibious. The Celestial dragon can breathe both air and water.

Unusual Nature. The Celestial Dragon doesn't require air, food, water, or sleep.

Multiattack. The Celestial Dragon makes two Holy Flare attacks.

Holy Flare. The Celestial Dragon shoots a flare of holy fire at an enemy within a range of 120ft. (2d12 Fire damage plus 3d8 Radiant Damage)

Death Flare. The Celestial Dragon shoots a flare of death at an enemy with a range of 120ft. (2d12 Fire damage plus 3d8 Necrotic damage)

Holy Breath Weapon. The Celestial Dragon breathes a line of Cold and Radiant damage to a range of 60 ft. (3d6 Cold damage plus 3d8 Radiant damage)

Death Breath Weapon. The Celestial Dragon breathes a line of Poison and Necrotic damage to a range of 60ft. (3d6 Poison damage plus 3d8 Necrotic damage)

Spellcasting. The Celestial Dragon casts one of the following spells, requiring no Material components and using Wisdom as the spellcasting ability (spell save DC 18):

At Will: Detect Evil and Good, Shapechange (Beast or Humanoid form only, no Temporary Hit Points gained from the spell, and no Concentration or Temporary Hit Points required to maintain the spell), Misty Step, Spare the Dying,
3/Day Each: Fireball, Star Splinter, Divine Word

Divine Aid (2/Day). The Celestial Dragon casts Cure Wounds, Lesser Restoration, or Remove Curse, using the same spellcasting ability as Spellcasting.