The Breakthrough Card System (BCS) is not a trick, but rather a system with which many impressive card tricks can be performed. The key is a special deck of cards that can be cut and freely handled by spectators, but which allows the magician to perform baffling feats of mentalism.
The secret of the BCS is that there is only one kind of card in the deck. However, this one card is a very special, precision-crafted, lenticular image designed so that, depending on the angle at which the card is viewed, it can appear as any one of the 52 cards in a standard deck! So when the deck is spread for a spectator, each of the cards is viewed from a slightly different angle and it appears that the cards are all different! Once the magician has memorized the cards and angles, a huge variety of effects is possible.
For example, let's say that the magician is doing a blackjack demonstration and needs a seven to give the spectator 21. While turning the card on top of the deck over, the magician surreptitiously slips a few grains of sand beneath the card, placing them so that the card will be at the correct angle from the spectator's perspective (the closer to the "down" edge the grains are, the higher the angle). Instant 7 of clubs (or of any suit the magician likes).
In another effect, the magician asks a spectator to put the deck beneath the table, choose a card and random, and turn it face-up in the face down deck. The magician then reveals which card is turned over and spreads the deck to prove the prediction. Again, it's just a matter of having the deck at the right angle when spread to show the card the magician predicted. What could be easier!
And, of course, if a spectator chooses a card, the magician need merely note the angle at which it is being viewed to know the card the spectator sees.
The only difficulty with the BCS is that the magician must keep track of what cards have already been shown. It wouldn't make much sense to have six or seven sevens appear during an effect (although the deck is quite capable of that, if it's what the magician desires). But this is a small point given the deck's incredible flexibility.
If you can find Osterlind's secret magic sales Web site, you can contact him directly and purchase a BCS for only a few thousand dollars. And as any mentalist will tell you, it's worth every penny!