Attila the Thunder Turtle

Hold Breath. Attila can hold his breath for up to two hours.

Unwieldy Shell. The prone condition indicates that Attila has been flipped onto his back. Attila has advantage on all ability checks and saving throws against any effect which would knock him prone. While prone, Attila cannot use Destructive Stomp or Carapace Slide. In order to stand up, Attila must use his action and all of his movement.

Multiattack. Attila makes two attacks: one with his bite and one with his tail. He can't make both attacks against the same target. If both Attila and the target are suspended in water, Attila may substitute one tail attack for two claw attacks.

Bite. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 3d12 + 5 slashing damage. If the target is a Medium or smaller creature, it is grappled (escape DC 16). Until this grapple ends, Attila can't bite another target.

Tail. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 3d8 + 5 bludgeoning damage. If the target is a Medium or smaller creature, it must succeed on a DC 16 Strength saving throw or be pushed up to 10 feet away from Attila.

Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., 1 target. Hit: 3d8 + 5 slashing damage.

Destructive Stomp (Recharge 5). Attila pounds his feet against the ground, discharging destructive energy. Each creature in a 20-foot cube originating from Attila must make a DC 15 Constitution saving throw. On a failed save, a creature takes 4d8 thunder damage and is pushed 10 feet away and knocked prone. On a successful save, the creature takes half as much damage and isn't pushed or knocked.

Chain Lightning Breath (Recharge 6). Attila exhales lightning in a 100-foot line that is 5 feet wide. Each creature in that line must make a DC 15 Dexterity saving throw, taking 8d6 lightning damage on a failed save, or half as much damage on a successful one. A creature grappled by Attila's jaws automatically fails this saving throw and is launched 50 feet in the direction of the lightning bolt, landing prone. If the lightning bolt strikes a surface within its 100-foot length, it arcs to the three nearest creatures other than Attila within 30 feet of where the lightning bolt strikes. These creatures must make a DC 15 Dexterity saving throw, taking 4d6 lightning damage on a failed save, or half as much damage on a successful one. Creatures caught in the initial lightning bolt cannot be targeted by the arcing bolts, and are excluded from the count to determine the nearest creatures.

Carapace Slide (Recharge 5-6). Attila withdraws into his shell and launches himself along the ground, gaining the effects of Shell Defense. Attila slides 60 feet, moving through the space of Large or smaller creatures in his path and reflecting off of any surfaces and Huge or larger creatures that he strikes. Any creature or object that Attila strikes must make a DC 16 Dexterity saving throw, taking 3d12 bludgeoning damage on a failed save, or half as much damage on a successful one.

Shell Defense. Attila withdraws into his shell. Until he emerges, he gains a +4 bonus to AC and has advantage on Strength and Constitution saving throws. While in his shell, Attila's speed is 0 and can't increase, he has disadvantage on Dexterity saving throws, he can't take reactions, and the only action he can take is a bonus action to emerge.

Rapid Retreat (1/day). Attila quickly withdraws into his shell in response to an attack that would hit him or an effect that would force him to make a Strength or Constitution saving throw, gaining the effects of Shell Defense. Unless Attila is prone, he then thunderously crashes to the ground. Each creature within 10 feet of Attila must make a DC 15 Constitution saving throw. On a failed save, a creature takes 4d8 thunder damage and is pushed 10 feet away and knocked prone. On a successful save, the creature takes half as much damage and isn't pushed or knocked.