Multiattack

The dragon attacks once with its bite and twice with its claws. In place of its bite it can use Psionic Wave.

Bite

Melee Weapon Attack: +15 to hit, reach 15 ft., one target. Hit: 30 (4d10 + 8) piercing damage plus 9 (2d8) thunder damage.

Claws

Melee Weapon Attack: +15 to hit, reach 10 ft., one target. Hit: 21 (3d8 + 8) slashing damage.

Psionic Wave

The dragon psionically emits a wave of crushing mental pressure. Each creature within 20 feet makes a DC 21 Wisdom saving throw taking 22 (4d10) psychic damage on a failed save or half damage on a success. Confused creatures make this saving throw with disadvantage.

Maddening Breath (Recharge 5-6)

The dragon screams stripping flesh from bones and reason from minds in a 90-foot cone. Each creature in that area makes a DC 21 Constitution saving throw taking 88 (16d10) thunder damage on a failed save or half damage on a success. Creatures that fail this saving throw by 10 or more are also psionically confused until the end of their next turn.