Liner - created by Bond Lee & Alexander Stefanus, produced by MS Magic. Here's how it works: A spectator picks a card freely, signs their name on it, and puts it back into a random place in the middle of the deck. The magician draws a black line on the top card; suddenly, the black line moves instantly, jumps to different positions, and then disappears in a flash. When the magician spreads out the entire deck, it is revealed that a black line has appeared on the back of one card-and that card is exactly the one the spectator signed at the beginning. This magic trick features a complete and powerful routine, with highly visual effects and very simple operations, making it suitable for all close-up magicians.

Description from Penguin Magic