Bite

Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 52 (7d12 + 7) piercing damage. If the target is a creature it is grappled (escape DC 21). Until this grapple ends the dragon turtle can't bite a different creature and it has advantage on bite attacks against the grappled creature.

Ram

Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 46 (6d12 + 7) bludgeoning damage. This attack deals double damage against objects vehicles and constructs.

Tail

Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 46 (6d12 + 7) bludgeoning damage. If the target is a creature it makes a DC 21 Strength saving throw. On a failure it is pushed 15 feet away from the dragon turtle and knocked prone.

Steam Breath (Recharge 5-6)

The dragon turtle exhales steam in a 90-foot cone. Each creature in the area makes a DC 20 Constitution saving throw taking 52 (15d6) fire damage on a failed save or half as much on a successful one.

Lightning Storm (1/Day)

Hundreds of arcs of lightning crackle from the dragon turtle. Each creature within 90 feet makes a DC 17 Dexterity saving throw taking 35 (10d6) lightning damage on a failure or half damage on a success.