Four spectators each choose a card. By means of telepathy you try to discern which cards were chosen. Ask each participant to raise their hand as they hear the name of their card.
You name four cards. But, no hands go up. Oops!
No, problem. Point to an envelope on the table, which, you explain contains the four chosen cards. You remove a Jumbo Card from the envelope and show its face. All 52 cards are printed on the Jumbo Card, and you point out their cards. The spectators are less than impressed. But, you continue.
Clearly you have failed to name the four chosen cards, so you tear up the Jumbo Card!
When you put the pieces together, the card has been magically restored. When you show the face of the card, the 52-on-1 Card has been transformed into one card with only four poker-size cards for its face. The four selected cards! Contains enough material for 25 performances. Great for close-up or stage. Great magic.