A secret hidden in most decks of cards. You already have it. It can be used for magic or mentalism effects as it will add something "bizarre" or intriguing to your card tricks. Or as a double kicker. YOu will use it in your existing routines or invent new ones. Guaranteed. A typical example is "The Fine Print" by Jay Sankey. The difference is that you can do it impromptu, without buying a gimmick, and with some touch of mentalism.
"You remove a playing card from a deck of cards and leave it face down on the table as a prediction. A spectator then selects a card from the deck, but when your prediction is turned over, it is wrong! (Hey! It's normal as all the cards in a deck are unique.) Upon closer inspection, the prediction is revealing itself to be true, and everything can be justified."
Guess this card: You place a card on the table face down, and the spectator has to guess it. This is repeated a couple of times.
Do as I do: There is some dealing and spelling, but I am sure you will find times to perform this, and you will learn two interesting principles.
Out of the Blue: A quick trick you can try with busy people. "I have a card in my pocket. It's a black card. What is it?"
Very quick guess: Idem but for very busy people.
Affinity: The spectator inserts a business card in the deck. Then the card below and the card above are turned over. They do not match, but after a closer look, they do.
The matching game: An adaptation of an Howard Adams principle.
Better than nothing: A workaround to predict almost any card based on the "Hidden" concept.
1st edition 2018, 30 pages.
word count: 7103 which is equivalent to 28 standard pages of text