Sangromancy

You have gained the power to fuel your magical power at the expense of your own lifeforce.

• When you cast a spell, instead of spending a spell slot, you may choose to spend a number of hit dice equal to the spell slot level, up to a maximum of a 5th level slot.
• When you cast a spell that requires a saving throw, you can choose to spend a number of hit dice up to your Constitution modifier. Increase your spell save DC for the spell cast by a number equal to half the amount of hit dice you spent.

When you spend hit dice to use these powers, you take damage equal to the amount of hit dice spent.