Farland: Blood Magic

You have learned the forbidden secrets of Blood Magic, invented long ago by the Necromancer Cutalak of the Cult of Darkness. You gain the following benefit:

• Instead of spending a spell slot to cast a spell, you can cause yourself 1 of your hit die of damage per level of the spell. If you are multi-classed, you may chooose which hit die, but it must be from a spellcasting class. Wounding yourself counts as the somatic component of the spell you are casting, and you must be holding a weapon that deals slashing or piercing damage (unless you can readily cut yourself on something). If you have resistance to slashing or piercing damage, your resistance doesn't function against the damage you cause yourself when using Blood Magic.

Credit: Farlandworld.com