A barghest who slays an opponent and consumes their soul gains hit dice. For every three opponents slain, the barghest gains one hit die, to a maximum of 12 HD. For each HD it gains, it also increases its Strength, Dexterity and Constitution by 1, and its AC increases by 1. For every 3 HD thus gained, the damage for its natural attacks increase by one die type (d8, d10, d12), and its effective Challenge Level increases by 1, with commensurate increase in Proficiency bonus. At 10 HD, its size increases to Large, and its shapechange allows for shifting to hobgoblin or worg forms instead of goblin and wolf.