Adult Sun Dragon

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

Innate Spellcasting.

The dragon’s innate Spellcasting Ability is Charisma (spell save DC 19). It can innately cast the following Spells, requiring no material components:

At will: heat metal, light

3/day each: prismatic spray

Brilliant Corona.

Any creature that starts its turn within 30 feet of the dragon must succeed on a DC 19 Constitution saving throw or be blinded. If a creature’s saving throw is successful, the creature is immune to the dragon’s Brilliant Corona for the next 24 hours. Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it can't see the dragon until the start of its next turn, when it can avert its eyes again. If the creature looks at the dragon in the meantime, it must immediately make the save.

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

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., one target. Hit: 18 (2d10 + 8) piercing damage plus 6 (2d6) fire damage.

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 8) slashing damage.

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 8) bludgeoning damage.

Frightful Presence. Each creature of the dragon's choice that is within 120 ft. of the dragon and aware of it must succeed on a DC 19 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 the dragon's Frightful Presence for the next 24 hours.

Solar Breath (Recharge 5–6).

The dragon exhales a small, slow moving fireball to a space within 60 feet of it. The fireball lingers in place, hovering and emitting 60 ft. of bright sun-light. As a reaction, any time another creature starts or ends its turn, the dragon may force all lingering fireballs to explode, searing the 60 feet around each fireball with solar energy. Each creature in that are must make a DC 21 Dexterity saving throw, taking 35 (10d6) fire damage and 35 (10d6) radiant damage on a failed save, or half as much on a successful one.

Legendary Actions

The dragon 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 their 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 ft. of the dragon must succeed on a DC 22 Dexterity saving throw or take 15 (2d6 + 8) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.