Legendary Resistance (1/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Innate Spellcasting. The Dragon's spellcasting ability is Charisma (spell save DC 14). It can innately cast the following spells, requiring only verbal components: 

At will: detect evil and good, detect magic, detect thoughts
2/day each: bless, create food and water, cure wounds, lesser restoration, protection from poison, sanctuary, shield

Shielded Mind. The Dragon has advantage in saves to avoid to scrying and to any effect that would sense its emotions, read its thoughts, or detect its location.

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, hit points, 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.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) piercing damage.  The target must succeed on a DC 12 constitution saving throw or be poisoned for 24 hours Until this poison ends, the target is unconscious. Another creature can use an action to shake the target awake

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage.

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

Radiant Breath. The dragon exhales Radiant Energy in a 90-foot line that is 10 feet wide. Each creature in that line must make a DC 14 Dexterity saving throw, taking (8d8) radiant damage on a failed save, or half as much damage on a successful one.

Slowing Breath. The dragon exhales gas in a 90-foot cone. Each creature in that area must succeed on a DC 14 Constitution saving throw. On a failed save, the creature can't use reactions, its speed is halved, and it can't make more than one attack on its turn. In addition, the creature can use either an action or a bonus action on its turn, but not both. These effects last for 1 minute. The creature can repeat the saving throw at the end of each of its turns, ending the effect on itself with a successful save.

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, hit points, 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.