Ask a spectator to shuffle the cards.
Have the spectators look through the shuffled deck and agree on a numbered / non-face card (that’s any card from 2 to 10.) Ask the spectators to show each other the group selection but not to say the number out load. Ask the spectator to place their chosen card face down on the table and to place the big pile face down next to their chosen card.
Now have the spectator pick up the big pile and begin to silently count cards off the top placing them face down on top of their chosen card. They will count off the same number of cards equal to the number on their chosen card. For example if their chose card is the 3 of diamonds.. they will silently count 3 cards off the big pile placing them face down onto their 3 of diamonds. Once the spectator is done ask them to let you know.
Now ask the spectator to place the small pile they’ve created face down on top of the big pile and to hold all the cards face down in their hand.
Explain to the spectator that you will now call upon the forces of the universe to find their card. You will use their hands and sight to correctly pick the groups chosen card.
Have the spectator turn over the top card placing it face up on the table and calling out it’s value.. Jack of hearts, 3 of diamonds, etc.
(Here’s where the magic happens.) Disregard the first card as it’s a throwaway. Ask them to place the next card face up. In your mind assign it the slot value of #1 This card two will never be “their choice” it’s simply a place holder. Remember we asked them to find a card between 2 and 10. Now ask them to place the next card face up. Assign this card the #2 slot. Is this card a two of something? two of diamonds, clubs, etc.. if so you have a match! Even if it does match continue to have them lay the next card face up. which in this case would be #3. Continue this all the way to slot 10. When the # on the card matches your “slot count” you have a match!
Performance tip: From time to time you will get multiple cards matching your slot number.. let’s say slot #6 has a 6 of clubs and slot #8 has an 8 of diamonds. Here’s where luck and theater converge. You have to pick one randomly.. lets say you pick the 6 of clubs and it’s not their chosen card. Remind them you’re reading the card through their eyes.. ask the group to stare at their chosen card… then say, “Yes.. YES! I’ve got it!… it’s the 8 of diamonds!” (the only other choice that matched your slot number).