Ancient Angelic dragon

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

Beast of light. When dealing radiant damage the ancient Angelic dragon breaks through radiant resistance and treats radiant immunity as resistance

Creature of the Divine. When dealing radiant damage to fiends or Undead it will gain an extra five damage dice 

Radiant natural weapons. The ancient angelic dragon’s natural weapons count as magical

To those who serve. If there are any paladins or clerics that the ancient Angelic Dragon considers an ally in a 30-foot radius of itself they will gain Advantage on all Attack rolls made and the dragon is allowed to expend a legendary action to Said Paladin or cleric to regain up to three spell slots of fifth level and lower.

Multiattack. The dragon can use its Sacred Presence. It then makes three attacks: one with its bite and two with its claws.

Heavenly bite. Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 19 (15d10 + 19) piercing damage plus 7 (30d8) Radiant damage.

Righteous claw. Melee Weapon Attack: +15 to hit, reach 5 ft., one target. Hit: 15 (8d6 + 19) slashing damage.

Heavenly Tail. Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 17 (7d8 + 19) bludgeoning damage.

Sacred Presence.As a mighty holy being the ancient Angelic dragon holds the ability of sacred presence meaning that creatures within a 120 radius of the creature that it considers allies or good aligned creatures Gain half of the dragons maximum hit point total as temporary hip points and have the choice to either take in new temporary points when they gain temporary hit points or choose to keep the total that they had before. If a fiend Undead or evil aligned creature is in 120 ft of the Dragon they will have to succeed on a DC 30 Wisdom saving throw or be [Condition]Frightened[ condition] For As long as they are in the dragon's sacred presence on any subsequent turn they can choose to make an additional saving throw.

Radiant Breath (Recharge 5–6). The dragon exhales Radiant light in a 60-foot long and 15 ft wide Line. Each creature in that area must make a DC 26 Dexterity saving throw, taking 63 (70d10) Radiant damage on a failed save, or half as much damage on a successful one.

The dragon can take 8 legendary actions, choosing from the options below. The dragon regains spent legendary actions at the start of its turn.

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 10 feet of the dragon must succeed on a DC 22 Dexterity saving throw or take 15 (5d6 + 19) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

Breath attack. The dragon attacks with its breath attack

can take 3 Mythic actions, choosing from the options below. Only one Mythic action option can be used at a time and only at the end of another creature's turn.  regains spent Mythic actions at the start of  turn

Golden radiance. Explodes in a massive Golden Light Making all creatures caught in it and do a constitution saving throw DC 30 or take (30d6)Radiant damage In a 100 ft sphere around itself if any fiends or UndeadAre caught in the explosion they will immediately fail the saving throw.

Shimmering Skies. The ancient Angelic Dragon summons Two solars As they roll initiative and join combat 

Valhallen combat. The ancient Angelic Dragon lets out a mighty Roar forcing all enemy creatures in initiative to lose three points to their initiative role and giving all allies extra (3d6)Radiant damage And if they were a paladin or cleric they are then allowed to double the damage of their Divine strike or Divine smite once every turn for a minute.

To Heroes alone. The ancient Angelic dragon chooses a single Target and gives them advantage on all saving throws; all ability checks immunity to necrotic damage, a +5 bonus to hit and if the creature they are trying to hit is a fiend or Undead they will gain advantage.

Legendary resistance recharge. Recharges all expanded uses of legendary resistance it may  have lost

Breath attack recharge. Recharges the ancient Angelic dragons  radiant breath attack instantly if it's breath attack was already charged then it will deal double damage