Witch's Cauldron

During your end-step, reveal the top card of your library. If it is a Black or Blue spell, Enchant it to this card as an Aura. Otherwise exile it.
{t}: Pay {x} X being equal to one of the auras Enchanted to this card by it's own effect's converted mana cost. Cast that spell as though it were in your hand.
"There is no magic when noone no longer believes." --Hilda Lewis