The strategy is simple, first use Draco's ability to look at your opponents hand then, use your last action on Platform 9 3/4 to gain 2 more turns, then you use Illegibilus to discard a card from you hand, the repeat the process until your opponent has no cards in his hand, then put down Gringotts Car Ride to make your opponent discard the first card he or she draws, they will have to use both their actions just to draw cards. The only reason Snape is in here is because of his ability to return 7 cards to the deck. Because don't ya want back the cards that you used to get rid of your opponent's hand ??! OF course you Do.