Amphibious. The dragon can breathe air and water.

Spellcasting. The dragon is a 9th-level spellcaster. Its spellcasting ability is Intelligence (spell save DC 14, +6 to hit with spell attacks). The dragon has the following wizard spells prepared:

Cantrips (at will): fire bolt, light, mage hand, prestidigitation

1st level (4 slots): detect magic, mage armor, magic missile, shield

2nd level (3 slots): misty step, suggestion

3rd level (3 slots): counterspell, fireball, fly

4th level (3 slots): greater invisibility, ice storm

5th level (1 slot): cone of cold

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 plus 7 (2d6) poison damage.

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

Poison Breath (Recharge 5–6). The dragon exhales poisonous gas in a 30-foot cone. Each creature in that area must make a DC 14 Constitution saving throw, taking 42 (12d6) poison damage on a failed save, or half as much damage on a successful one.

Alter Shape. The dragon magically transforms into a raven or a mage and retains its alignment, damage immunities, hit points, and Hit Dice, as well as its Intelligence, Wisdom, and Charisma scores. This transformation ends if the dragon is reduced to 0 hit points or if it uses another bonus action to end it.