Infernal Bargain

Rather than pay the mana cost of spells you cast, you may get X debt counters, where X is the converted mana cost of that spell. (A player with one or more debt counters can't cast spells. You may pay {1} at any time to remove a debt counter from yourself.)
You can't cast more than one spell each turn.
At the begining of your end step, you lose 1 life for each debt counter you have.