Amphibious. the Shark can breathe air and water.

Blood Frenzy. The shark has advantage on melee attack rolls against any creature that doesn't have all its hit points.

Keen Hearing and Smell. The shark has advantage on Wisdom (Perception) checks that rely on hearing or smell.

Pounce. If the shark moves at least 20 feet straight toward a creature and then hits it with a claw attack on the same turn, that target must succeed on a DC 14 Strength saving throw or be knocked prone. If the target is prone, the shark can make one bite attack against it as a bonus action.

Swimming Leap. With a 10-foot swimming start, the shark can long jump out of or across the water up to 25 feet.

Multiattack. The shark makes three attacks: one bite attack and two claw attacks.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 15 (2d10 + 4) piercing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) piercing damage.

Mutate. If the shark mutates, it can move its full movement speed towards a creature and make a claw attack with advantage. The target then must make its saving throw against the shark's pounce ability with disadvantage.