Helgot Warbeast (5e Creature)
From D&D Wiki
Huge monstrosity, unaligned
Charge. If the warbeast moves at least 10 feet straight toward a target and then hits it with a claw attack on the same turn, the target takes an extra 9 (2d8) slashing damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be pushed up to 10 feet away and knocked prone.
Rampage (1/Day). If the warbeast is reduced to half its maximum hit points or is struck by a critical hit, it enters a violent rage. While enraged, it has a +2 bonus to its attack rolls; it has advantage on Strength checks and saving throws; and it gains resistance to bludgeoning, piercing, and slashing damage. Its rampage only ends after 10 minutes or if it falls unconscious.
Beak. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 25 (3d12 + 6) piercing damage.
Claws. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 24 (4d8 + 6) slashing damage.