"X Marks the Spot" is a completely self-working effect that happens almost entirely in the spectator's hands!

The magician signs a card and looses it into the deck. The deck is then handed to a spectator to shuffle behind their back. The spectator draws a giant "X" on the back of a random card in the deck. The "X" card is revealed to be the same one the magician signed at the beginning of the effect!

The best part is that the effect is so easy to perform, you will literally be performing it as soon as you learn it!