Amphibious. The dragon turtle can breathe air and water.
Multiattack. The dragon turtle makes three attacks: one with its bite and two with its claws. It can make one tail attack in place of its two claw attacks.
Bite. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 26 (3d12 + 7) piercing damage.
Claw. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 16 (2d8 + 7) slashing damage.
Tail. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 26 (3d12 + 7) bludgeoning damage. If the target is a creature, it must succeed on a DC 20 Strength saving throw or be pushed up to 10 feet away from the dragon turtle and knocked prone.
Steam Breath (Recharge 5-6). The dragon turtle exhales scalding steam in a 60-foot cone. Each creature in that area must make a DC 18 Constitution saving throw, taking 52 (15d 6) fire damage on a failed save, or half as much damage on a successful one. Being underwater doesn't grant resistance against this damage.