Multiattack. It then makes 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 (2d10 + 6) piercing damage.

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

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Psychic Breath. The dragon exhales psychic blast in an 30-foot cone. Each creature in that cone must make a DC 17 Wisdom saving throw, taking 54 (12d8) psychic damage on a failed save, or half as much damage on a successful one.

Deafening Breath. The dragon exhales sleep gas in a 30-foot cone. Each creature in that area must succeed on a DC 17 Constitution saving throw or fall deafened for 1 minutes. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Change Shape. The dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own., or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (Dragons choice). 

In a new form, the dragon retains its alignment, hit points, hit dice, ability to spear, proficiencies, Legendary Resistances, Lair Actions and Intelligence, Wisdom and Charisma Scores as well as this action. The Dragons statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.