What you get:

A regular deck (red in my case) plus some extra cards, plus 12 dice.

The routine:

You place a prediction (this could be on the back of your business card) on the table. You could have this already prepared and in the case or you could write it out on your business card before you present the trick. Either way your prediction can be a plain sight all through the effect.

You get a spectator to hold the 12 dice in both hands, give them a shake and let them land on the table.

Ask the spectator to arrange the dice in one long line.

As they are doing this, a very quick glance at this point will establish whether the trick will work - it takes a couple of seconds and the chances are very, very high that it will work straight away.