Multiattack

The dragon can use its Mesmerizing Presence. It then makes three attacks: one with its bite and two with its claws.

Bite

Melee Weapon Attack: +14 to hit, reach 10 ft., Hit: 19 (2d10 + 8) piercing damage.

Claw

Melee Weapon Attack: +14 to hit, reach 5 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

Tail

Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 17 (2d8 + 8) bludgeoning damage.

Mesmerizing Presence

Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 20 Wisdom saving throw or become charmed by the dragon for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the dragon's Mesmerizing Presence for the next 24 hours.

Lightning Breath (Recharge 5-6)

The dragon exhales lightning in a 90-foot line that is 5 feet wide. Each creature in that line must make a DC 21 Dexterity saving throw, taking 55 (10d10) lightning damage on a failed save, or half as much damage on a successful one.

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 (the dragon's choice). In a new form, the dragon retains its alignment, hp, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form. The dragon can choose to transform only part of its body with this action, allowing it to sprout rabbit-like ears or a humanoid head. These changes are purely cosmetic and don't alter statistics.