Ancient Solar Dragon

Ancient Solar Dragon
CR 21Gargantuan Dragon, Neutral
Reveal Stat Block
Armor Class
18 (natural armor)Hit Points
425 (23d20 + 184)Speed
30 ft., fly 120 ft. (hover)str
28
+9
dex
15
+2
con
26
+8
int
17
+3
wis
18
+4
cha
16
+3
Traits
Flyby.The dragon doesn't provoke opportunity attacks when it flies out of an enemy's reach.
Legendary Resistance (3/Day).If the dragon fails a saving throw, it can choose to succeed instead.
Nebulous Thoughts.Magical attempts to read the dragon's mind or glean its thoughts fail automatically.
Siege Monster.The dragon deals double damage to objects and structures.
Unusual Nature.The dragon doesn't require air.
Actions
Multiattack.The dragon makes one Bite attack and one Tail attack.
Bite.mw 16 to hit, reach 20 ft., one target. ({@damage 3d6 + 9) piercing damage plus 10 (3d6) radiant damage.
Tail.mw 16 to hit, reach 20 ft., one target. ({@damage 1d8 + 9) bludgeoning damage.
Photonic Breath 5.The dragon exhales a flashing mote of radiant energy that travels to a point the dragon can see within 240 feet of itself, then blossoms into a 40-foot-radius sphere centered on that point. Each creature in the sphere must make a 23 Constitution saving throw, taking 66 (12d10) radiant damage on a failed save, or half as much damage on a successful one.
Legendary Actions.The creature can take 3 legendary actions...
Tail Attack.The dragon makes one Tail attack.
Blinding Brilliance (Costs 2 Actions).The dragon emits magical light in a 30-foot-radius sphere centered on itself. Each creature in this area must succeed on a 23 Wisdom saving throw or be blinded until the end of its next turn.