Do you remember a time when you hand a full hand? This card remembers. This card us considered one of the best in Magic and I think it's pretty obvious to see why. It's massive amounts of instant-speed card advantage for you on a stick! Let's say you're late into a game and you've only got a couple cards in hand that aren't exactly that useful right now. Break this open and you've got seven brand new cards that you can use this turn whereas your opponent only gets to look sad at all the non-Instant cards she's about to lose. Some of the other "combos" that people toss around: Megrim/Liliana's Caress, Underworld Dreams, Library of Leng, and Geth's Grimoire. All in all, a stellar card.
Pros: Draw seven at instant speed, massive card advantage if used on your turn
Cons: Seals your current hand (if it exists) in exile, must discard hand at end of turn