Catastrophic Aura(Volcano). A 5-foot aura of noxious fumes wafts around the dragon. Any creature which ends its turn within the aura must make a DC 17 Constitution saving throw or take 14 (4d6) poison damage.

Multiattack. The dragon can use Growing Aura and then make three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 17 (1d10 + 4) piercing damage plus 7 (2d6) fire damage

Claw. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 13 (2d6 + 6) slashing damage plus 3 (1d6) fire damage.

Growing Aura. The dragon's Catastrophic Aura expands its radius 10 feet. If the dragon uses this ability when its Catastrophic Aura is 25 feet, the dragon's aura explodes with energy and all creatures within 30 feet of the dragon must make a DC 17 Dexterity saving throw. Creatures who fail take 42 (12d6) fire damage and are on fire, taking 2 (1d4) fire damage at the start of their turns, creatures who succeed take half damage and are not on fire. A creature who failed the save and is on fire can extinguish the fire by using their action to make a successful DC 10 Dexterity saving throw on its turn. Once the dragon's aura explodes with energy it resets to 5 feet. Being struck with fire damage will activate this ability