Dara, Potent Spellcaster

Play with the top card of your library revealed.
Whenever an opponent casts a spell, if it shares a card type with the card revealed on top of your library, you may cast the top card of your library this turn as though it had flash without paying its mana cost, then you lose life equal to that card's converted mana cost. Otherwise, you may put that card on the bottom of your library.