High Fliers. The dragon can breathe in any area that has an amount of air, no matter how thin. It can hold it's breath for up to ten minutes at a time.

Azure Scales. The dragon's attacks are at advantage while underwater, and while submerged, grants the dragon resistance to bludgeoning, slashing and piercing damage. A creature who hits the dragon with an attack over two times (a third time, a sixth time or a ninth time) in a turn releases defensive mist, allowing the dragon to recharge it's breath and use it immediately.

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

Bite. Melee Weapon Attack: +12 to hit, reach 10 ft., one target. Hit: 17 (2d10 + 7) piercing damage plus 4 (1d8) cold damage.

Tail. Melee Weapon Attack: +12 to hit, reach 5ft, one target. Hit. 1d12+7 bludgeoning damage.

Cloud Breath (Recharge 5-6). The dragon exhales thick, heavy clouds in a 30ft radius around it. Each creature in that area must make a DC 18 Strength saving throw, taking 49 (12d8) cold damage on a failed save, or half as much damage on a successful one. Creatures who fail the saving throw also fall to the ground, unable to fly, even magically. Their weight is doubled, and they cannot swim properly until the end of the dragon's next turn. 

Drag (3/day). The dragon pushes or pulls a medium or smaller target with it's small arms, up to it's remaining movement speed in a direction.