Some folks enjoy unlocking the cards in Magic: The Gathering - Duels of the Planeswalkers 2013 one by one. If you're not one of those people, though, you're probably driven a bit mad right now, spending days at a time just trying to unlock the 30 cards for one deck so it can reach its full potential.
Fortunately, there's a way to alleviate the issue, as YouTube user 'wunderstudios' explains. The 'hack' is pretty simple: turn off AI Takeover, invite your friend to a game, have him concede, then rinse and repeat. Though you won't see the notification you've unlocked the card, it will be there in the Deck Manager. And of course, do the same courtesy for your friend afterward.
Using this method, you could feasibly have all cards for a given deck unlocked within about 10 minutes, and all cards for all decks unlocked in an afternoon.