DELPHI by Matt Pilcher 
A great piece of mentalism whereby the spectator has kept the prediction prior to the effect! 

A spectator first hides an envelope handed to them by the magician, and keeps it in their possession. They then choose 4 number cards completely at random. You and the spectator add up the numbers from all cards to arrive at a total random number. The spectator then counts down to that number in a deck of cards - a deck that had been previously shown to comprise different cards in no particular order. It couldn't be ANY fairer. Then the prediction, which has been in the spectator's pocket from the start, reveals that you correctly predicted which card they would select via this random number. NO switching the selected card, NO switching the prediction. The prediction is set before you even begin. 

Extras - Also thrown in are some optional extra predictions: 

- A prediction stating the pocket in which the spectator placed the prediction. 
- A prediction stating something about the number cards chosen by the spectator. 

Very much a hands-off effect and 99% self-working effect. 

Predicting the future JUST.GOT.REAL. 

Download the DELPHI video and enjoy performing this feat of mentalism.