Flyby.

The dragon doesn't provoke opportunity attacks when it flies out of an enemy's reach.

Unusual Nature.

The dragon doesn't require air.

Actions

Multiattack.

The dragon makes one Bite attack and one Tail attack.

Bite.

Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 12 (2d6 + 5) piercing damage plus 7 (2d6) radiant damage.

Tail.

Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 8 (1d6 + 5) bludgeoning damage.

Photonic Breath (Recharge 5–6).

The dragon exhales a flashing mote of radiant energy that travels to a point the dragon can see within 120 feet of itself, then blossoms into a 20-foot-radius sphere centered on that point. Each creature in the sphere must make a DC 17 Constitution saving throw, taking 44 (8d10) radiant damage on a failed save, or half as much damage on a successful one.

Young Solar Dragon