Imagine a spectator choosing any card in the deck, they sign the card on the face and you then lose it in the deck. Then you show the spectator a card with a cut out shape on it; you place it on top of the deck. In an instant the spectator's signed card appears through the cut out.
Very visual, very easy to do. Enjoy performing 'REACTION'.
Custom made gimmick
Instructional DVD with full explanations.