The tantalizer

You need a full deck of 52 cards for this trick, which the spectator can shuffle.

Start by asking the spectator to choose a card, take it and remember it. Now riffle through the deck and ask them when to stop. Cut at that location, show them the top-half and ask them to put their card there. While they're doing that, take a glimpse a the card on the bottom of the other half, and then put that packet on top of their card.

Say you are now going to try to find their card. Take the deck and find your key-card : the card juste above it is the spectator's selected card. Starting from their card in the direction of your key-card, count 22 cards and cut at that location.

Give now the deck to the spectator and have them deal all the cards to you and them. Always keep their pile because "their card will always find them". Do this until there is only one card left : it will be the spectator's selected card.