Calamity Dragon Vorn'jaa

Cataclysmic Awakening (Recharges after a Short or Long Rest). If Vorn'jaa would be reduced to 0 hit points, his current hit point total instead resets to 500 hit points, he recharges his Breath Weapon, and he regains any expended uses of Legendary Resistance. Additionally, Vorn'jaa can now use the options in the “Mythic Actions” section for 24 hours. Award a party an additional 155,000 XP (310,000 XP total) for defeating Vorn'jaa after his Cataclysmic Awakening activates.

Legendary Resistance (5/Day). If Vorn'jaa fails a saving throw, he can choose to succeed instead.

Magic Resistance. Vorn'jaa has advantage on saving throws against spells and other magical effects.

Magic Weapons. Vorn'jaas attacks are magical.

Unusual Nature. Vorn'jaa doesn’t require food or drink.

Multiattack. Vorn'jaa makes one Bite attack and two Claw attacks. He can also use his Breath Weapon, if available.

Bite. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 23 (2d12 + 10) piercing damage plus 22 (4d10) force damage.

Claw. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 21 (2d10 + 10) slashing damage. If the target is a Huge or smaller creature, it is grappled (escape DC 20) and is restrained until this grapple ends. Vorn'jaa can have only one creature grappled this way at a time.

Tail. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 23 (2d12 + 10) bludgeoning damage. If the target is a creature, it must succeed on a DC 27 Strength saving throw or be knocked prone.

Breath Weapon (Recharge 5–6). Vorn'jaa uses one of the following breath weapons:

Devastation Breath. Vorn'jaa exhales a blast of energy in a 300-foot cone. Each creature in that area must make a DC 27 Dexterity saving throw. On a failed save, the creature takes 78 (12d12) damage of whichever type the creature is weakest to. On a successful save, the creature takes half as much damage.

Ruinous Beam. Vorn'jaa exhales a condensed beam of destructive energy from his mouth in a 300 foot line that is 10 feet wide. Each creature in the line must make a DC 27 Dexterity saving throw. On a failed save, the creature takes 100 (12d20) damage of whichever type the creature is weakest to. On a successful save, the creature takes half as much damage.

Vorn'jaa 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. Vorn'jaa regains spent legendary actions at the start of his turn.

Attack. Vorn'jaa makes one Claw or Tail attack.

Wing Attack (Costs 2 Actions). Vorn'jaa beats his wings. Each creature within 30 feet of him must succeed on a DC 27 Dexterity saving throw or take 17 (2d6 + 10) bludgeoning damage and be knocked prone. Vorn'jaa can then fly up to half his flying speed.

Arcane Spear (Costs 3 Actions). Vorn'jaa creates four spears of magical force. Each spear hits a creature of Vorn'jaa’s choice he can see within 120 feet of him, dealing 14 (1d10 + 10) force damage to its target, then disappears.

If Vorn'jaa’s Cataclysmic Awakening trait has activated in the last 24 hours, he can use the options below as legendary actions.

Bite. Vorn'jaa makes one Bite attack.

Inescapable Destruction. Vorn'jaa makes three perception checks.

Destructive Flare (Costs 2 Actions). Vorn'jaa flares with destructive energy. Each creature in a 60-foot-radius sphere centered on Vorn'jaa must succeed on a DC 27 Dexterity saving throw or take 39 (6d12) damage of whichever type the creature is weakest to. On a successful save, the creature takes half as much damage.