Legendary Resistance (3/Day, or 4/Day in Lair). If the dragon fails a saving throw, it can choose to succeed instead.

Multiattack. The dragon makes three Rend attacks. It can replace one attack with a use of Spellcasting to cast Shatter.

Rend. Melee Attack Roll: +12, reach 10 ft. Hit: 16 (2d8 + 7) Slashing damage.

Water Tank: The dragon has a water tank organ that it uses with a special breath organ to shoot boiling water at it's enemy's. Tank Capacity: 300ml of water

Moisture Sacrifice: (Ignore the bold) If the dragon runs out of water in it's tank it can sacrifice 10 hit points per 20ml of water its action would take

Refill: For every turn the dragon is fully submerged in water it will regain 20ml of water half that if it is only half submerged

Boiling Breath (Water Tank). Dexterity Saving Throw: DC 19, each creature in a 10 per 20ml used-foot-long, 5-foot-wide Line. Failure: 60 (1d10 per 20ml used) Fire damage. Success: Half damage.

Spellcasting. The dragon casts one of the following spells, requiring no Material components and using Charisma as the spellcasting ability (spell save DC 18):

At Will (cost 20ml per spell cast): Detect Magic, Invisibility, Mage Hand, Shatter
1/Day Each: Scrying, Sending Create or Destroy Water

Legendary Action Uses: 3 (4 in Lair). Immediately after another creature’s turn, the dragon can expend a use to take one of the following actions. The dragon regains all expended uses at the start of each of its turns.

Cloaked Flight. The dragon uses Spellcasting to cast Invisibility on itself, and it can fly up to half its Fly Speed. The dragon can’t take this action again until the start of its next turn.

Sonic Boom. The dragon uses Spellcasting to cast Shatter. The dragon can’t take this action again until the start of its next turn.

Tail Swipe. The dragon makes one Rend attack.