INK-redible By Nicholas Dakin
A brilliant gimmick that allows you to perform an impossible piece of magic. A spectator selects any card and signs the face. 4 black spots are drawn, one in each corner on the back of the signed card. No covering of any kind the spots visually jump one at a time into the top left corner. You have to see this to believe it. The signed card is now handed back to the spectator with ALL FOUR BLACK SPOTS IN ONE CORNER.
This is what real magic looks like.