Roll by Chris Congreave is the perfect mental card effect. 

Let me start by saying that since we have been playing with this effect at Alakazam, all of us have added it to our magic repertoire. It's so cool and you will love performing it! 

You show a deck of blue-backed cards to have one red-backed card sitting in it, stating it is a prediction of things to come. 

You out jog the red back card a little to show the words, "You Will Roll". 

The red-back card is pushed back into the deck and the deck is cut. 

You hand your spectator three normal dice and ask them to roll the dice a few times until they are happy with the outcome (please note they may also roll imaginary dice in their mind). 

Whatever number they land on, you count down from the top of the deck, placing each card face up on the table as you go. The card at their chosen number is placed face down. 

You now locate your prediction card in the deck and slowly reveal that not only have you predicted what number they would roll but also the card they landed on! 

Roll is super easy to do and comes with a special deck and full video instructions. 

Point to remember:

Works in any language
No duplicate cards
No long and short
No rough and smooth
No forces
Different numbers may be chosen
Different cards will be chosen
Instant reset
No memory work
May be performed on 1-3 spectators
Totally self-working!
Use with or without dice