Nykzos, The Restless

Sacrifice a creature: You may cast Nykzos, The Restless from your graveyard
Whenever you sacrifice a creature, if Nykzos is on the battlefield or in your graveyard, you may draw a card.
Sacrifice a creature: You may cast another creature card from your graveyard. That creature spells costs {x} less where X is equal to the
sacrificed creature's mana value.