Constant Acceleration - The longer Piercing Ox runs, the more damage it will deal with its Charge attack. Whenever Piercing Ox uses its Charge attack, add an amount of damage die equal to (Amount of ft. traveled / 15) rounding down.   Abyssal Potential. These monsters, when summoned as an ally of the summoner and not in a subjugation ritual, their hitdie will increase by an amount equal to (Caster Level - 10), and their damage die will increase by an amount equal to (amount of Ability Score Improvements - 2) they've had.