As an action, you can make a weapon attack in an attempt to leave a twisted wound that can’t be healed so easily. Add the stamina die to the attack’s damage (add half if you miss by 4 or less). On a hit, the creature must succeed on a Fortitude saving throw or its maximum health is reduced by the stamina die result for 1 hour. Any effect that removes a condition allows a creature’s maximum health to return to normal before that time passes.
You can increase the damage for each additional stamina die expended.