Whenever you discard a card, exile that card from your graveyard.
Pay 1 life: Exile the top card of your library face down. CAD$ 20.00 / CAD$ 25.00 credit. Aunque como tu has dicho no necesita necropotencia, con los infernal contract va que chuta. If you discard a card with madness and wish to cast it, Necropotence’s ability won’t exile that card. Necropotence was the first attempt, and the drawbacks added were to lose your draw step, delay the draw effect, and force the casting cost into all-black mana.