Kat, Magus of the Randomizer

Haste
{t}{1}{r}{r} Sacrifice Kat: Each player discards his or her hand, then draws seven cards.
{t}{2}{u}{u} Sacrifice Kat: Shuffle your library, then exile the top X cards, where X is one plus the number of spells cast this turn. Until end of turn, you may play cards exiled this way without paying their mana costs.