Amphibious. The dragon can breathe air and water.

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

Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 11 (2d6 + 4) piercing damage plus 2 (1d4) acid damage. If the target is Large or smaller, they are grappled (escape DC 14). Until this grapple ends, the target is restrained and the Dragon can't bite another target. 

Claw. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 9 (1d10 + 4) slashing damage.

Acid Breath (Recharge 5–6). The dragon exhales acid in a 15-foot cone. Each creature in that line must make a DC 14 Dexterity saving throw, taking 22 (4d10) acid damage on a failed save, or half as much damage on a successful one.

Tail Sweep: The Dragon swipes their tail in a 15-foot cone. Each Creature in that area must succeed on a DC 14 Strength saving throw or take 9 (1d10+4) bludgeoning damage and be pushed up to 10 feet away from the Dragon. Creatures that are grappled by the Dragon are not affected by this attack. 

Seek: The Dragon takes the Search Action

Respiratory Resistance: If the Dragon has a use of its Breath Weapon available and fails a saving throw, it can use its reaction to lose that use of its Breath Weapon and succeed instead. 

The Dragon can take 1 Legendary Action, choosing from the options below. The Dragon cannot take the same action on consecutive turns, and can only use each action once until their breath weapon recharges.

Obscuring Breath: The Dragon exhales heavy fog which settles in a 20 foot radius sphere centered on the Dragon. The fog heavily obscures the area and persists for 1d4 rounds. This fog can be dispersed early by a strong wind like Gust of Wind. 

Roar: The Dragon lets out a terrifying roar. Each enemy within 30 feet of them who can hear them must make a DC 12 Wisdom saving throw or be frightened of the Dragon for 1 minute (save ends at end of turn).

Buffeting Wings: The Dragon rears up and flaps its wings, buffeting nearby creatures with heavy winds. All creatures within 15 feet must make a DC 14 Strength saving throw or be knocked prone