Blood Mage

You’ve learned the secret art to infusing your magic with your own life force, sacrificing your own vitality to empower your spells.

You can use a dagger as an arcane focus.

Whenever you cast a spell of 1st level or higher which targets a hostile creature, you cut your self as part of the spells action or bonuce action.  Roll the damage dice taking that damage but adding double that to your spells damage.  You must make this free action before rolling attack or saving throws are made.

You must be wielding a dagger to perform this.