Amphibious. The Green Drake can breathe air and water.

Favored Terrain. In swampy areas, the Drake cannot be slowed by difficult terrain, magical or natural.

Camouflage. When the Drake is hiding in swampy terrain it has Advantage on Dexterity(Stealth) checks.

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

Multiattack. The Green Drake makes four attacks, one with its tail, two with its claws, and either a Bite or Water Jet attack.

Tail. Melee Weapon Attack: +16 to hit, reach 30ft., one target. Hit 30 (5d10 +5) piercing damage.

Claws. Melee Weapon Attack: +16 to hit, reach 10ft., one target. Hit 12 (2d6 + 5) slashing damage. Target makes a DC12 Constitution saving throw or gain the Poisoned condition. 

Bite. Melee Weapon Attack:  +16 to hit, reach 10ft., one target. Hit 10 (1d12 + 5) piercing damage plus 18 (4d4 + 8) acid damage. The Drake can grapple a hit target if it wishes, DC 20 Strength saving throw to escape. 

Water Jet (3/Day). The Drake swallows a few gallons of water and shoots it in a 80ft line that is 10 feet wide. Creatures in the line must make a DC 23 Dexterity saving throw or take 30 (6d6) bludgeoning damage and be knocked back 2d6x5ft and then fall prone, or half damage on a success and the creature remains standing. 

The Drake 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.

Tail. The Drake makes a tail attack.

Bite. The Drake makes a bite attack.

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

Death Roll (Costs 3 actions). If the Drake has a creature grappled from a bite attack, it can violently roll, damaging and disorienting the victim. The Death Roll must be used immediately after the grappled creature fails its Strength save on its turn. The target takes 75(14d10) Piercing damage and must make a DC18 Constitution saving throw or gain the Paralyzed condition until the end of their next turn.

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