Serendipity

(Nonexistent mana costs can't be paid.)
Serendipity is white and black.
Miracle and/or Madness {w/b} (You may cast this card for the specified cost when you draw it if it's the first card you drew this turn, or if you discard it to exile when you discard it. If discarded and not cast, put this in its owner's graveyard.)
Add {w}{w}. When spent, draw a card.