Flight orb. Though wingless, chiang lungs can fly magically due to a magic blue pearl embedded in their brains. If removed from the dragon, this pearl loses its magic but is still worth 1,000 gp. The dragon can cease or resume flight as a free action.

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Magic Resistance. The chiang lung has advantage on saving throws against spells and other magical effects.

Innate Spellcasting. The adult chiang lung's innate spellcasting ability is Wisdom (spell save DC 20). The adult chiang lung can innately cast the following spells, requiring no material components:

At will: augury, bane, bless, control weather, control winds, dispel good and evil (evil only), divination, invisibility, plane shift, remove curse

1/day: creation 

Amphibious. The chiang lung can breathe air and water. 

Cause rain. A chiang lung can breathe storm clouds, causing rain whenever and wherever it chooses. The rain lasts for 2d4 hours and extends in a two-mile radius centered on the dragon.

Control water. The chiang lung can use an ability like shape water but with a range of up to 1 mile. 

Detect thoughts. The chiang lung is constantly detecting the thoughts of creatures within 5ft of them. See the spell of the same name if a creature attempts to resist. 

Alternate form. Lung dragons can assume any humanoid form of Small to Large size as a standard action. This ability is similar to the polymorph spell but allows only humanoid forms. Whilst in this form they have advantage on all checks to hide their true self. 

Multi attack. The adult chiang lung uses its frightful presence, a  bite attack and two claw attacks. 

Bite. Melee Weapon Attack: +14 to hit, reach 10 ft., 1 target. Hit: 20 (3d8 + 8) piercing damage. 

Claw. Melee Weapon Attack: +14 to hit, reach 5 ft., 1 target. Hit: 14 (2d6 + 8) slashing damage. 

Tail. Melee Weapon Attack: +14 to hit, reach 15 ft., 1 target. Hit: 13 (1d10 + 8) bludgeoning damage. 

Frightful 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 18 Wisdom saving throw or become frightened 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 Frightful Presence for the next 24 hours.

The dragon can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time, and only at the end of another creature’s turn. The dragon regains spent legendary actions at the start of its turn.

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Tidal wave (Costs 3 Actions). The chiang lung creates a 25ft wide 40ft high tidal wave that moves 60ft. Each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 32 (8d8) bludgeoning damage and is knocked prone. On a successful save, a creature takes half as much damage and isn’t knocked prone. The water then spreads out across the ground in all directions, extinguishing unprotected flames in its area and within 30 feet of it, and then it vanishes.