e picks out one card randomly,then magician can easily identify what the audience chose.(There is a mark on the back)
The audience picks out one card randomly,then magician puts it into the cards and put the cards in a mess order. Then the magician can find out the chosen card fast.
The magician picks 4 Ace and puts it into the cards,then puts the cards in a mess order. Then the magician pulls out 4 cards,they are all Ace.
The deck can make many awesome card magic effect. Of course if your sleight is very excellent,then you can use it to perform more card magic tricks.