Spectator chooses a card, then the magician folds the spectator's card in the corner, then tears it.
After that, magician puts the card into the spectator's hand.
Then magician take another card, and folds it in the corner and tears it. And show, Boom, it changes to spectator's card torn and the magician's torn corner moves to spectator's hand.

Signed card, No forcing, and Visual!