Blood Frenzy. The shark has advantage on melee attack rolls against any creature that doesn't have all its hit points.
Water Breathing. The shark can breathe only underwater.
Actions
Bite. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) piercing damage. Smaller than a giant shark but larger and fiercer than a reef shark, a hunter shark haunts deep waters. It usually hunts alone, but multiple hunter sharks might feed in the same area. A fully grown hunter shark is 15 to 20 feet long.
RollQuest ships the D&D 2014 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.