The magician takes "two" decks from his pocket and sets them on the table -one deck is REAL and one deck is INVISIBLE!
Ask a spectator to pick any card from the imaginary invisible deck, a completely free choice.
Ask the spectator to name outloud the card they chose.
The visible deck is then removed from the box and spread out face up, to reveal one face down card in the face up deck. This card is turned over, it is the freely selected card.
Easy to perform miracle deck effect!