Blood Sacrifice

You use your own life force to strengthen your spells and harm your foes. As an additional cost for casting any spell of 1st level or higher, you may expend any number of available hit dice. Roll the expended number and take necrotic damage equal to the number rolled. If the spell targets a single enemy, that enemy takes the same amount of necrotic damage in addition to the spells normal damage. If the spell targets multiple enemies, or an area of effect, half number rolled is dealt to all targets as necrotic damage.