Black Tidemaw

Amphibious. The Black Tidemaw can breathe air and water.

Blood Frenzy. The Tidemaw has advantage on melee attack rolls against any creature that doesn’t have all its hit points while the Tidemaw is in water.

Shadow in the Deep. While in dark water, deep ocean, or heavy fog, the Tidemaw has advantage on Stealth checks and creatures have disadvantage on Perception checks to detect it.

Multiattack. The Black Tidemaw makes one Bite attack and one Tail attack.

Abyssal Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 22 (3d10 + 5) piercing damage. If the target is Large or smaller, it must succeed on a DC 16 Strength saving throw or be grappled. While grappled, the target is restrained.

Crushing Tail. Melee Weapon Attack: +8 to hit, reach 15 ft., one target. Hit: 17 (3d8 + 5) bludgeoning damage. The target must succeed on a DC 15 Strength saving throw or be knocked prone.

Death Roll (Recharge 5–6). If the Tidemaw has a creature grappled, it spins violently in the water. The grappled creature takes: 27 (6d8) slashing damage and must succeed on a DC 16 Constitution saving throw or become stunned until the end of its next turn.

Sudden Surge. When a creature within 15 ft. deals damage to the Tidemaw while it is in water, the Tidemaw can move up to half its swim speed without provoking opportunity attacks.