Ultimate Prediction Card Trick

The Effect: The magician cuts the deck into 2 piles and asks a spectator to select a pile to use, once the spectator has chosen their pile, the magician will ask the spectator to give those cards a good shuffle and the magician will do the same with the remaining pile and then both the spectator and magician will cut anywhere inside their pile and switch those piles of cards with each other and shuffle the face up cards into their face down piles so both the spectator and the magician will now have a pile of cards with a random mix of face up and face down cards.