Pack Tactics. The shark has advantage on attack rolls against a creature if at least one of the shark's allies is within 5 feet of the creature and isn't incapacitated. Water Breathing. The shark can breathe only underwater.
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft, one target. Hit. 6-8-12 2d4+4 piercing damage. When the Shark bites you, you must succeed on a DC10 Dexterity or be grappled by the Shark. A shark that is grappling a target cannot attack another creature. A creature can escape the grapple by either themselves or a ally spending an action to escape its jaws, and must succeed on either a DC 12 Dexterity or Strength check. Leaving the grapple deals 5-6-8 1d4+4 piercing damage. Thrash. Melee Weapon Attack: Must be grappled at start of the Sharks turn, one target. Automatically hits. 8-12-22 4d4+4 Piercing Damage. A creature that is Thrashed must succeed on a DC10 Constutition check or become stunned, if it is already stunned, it falls unconsious.