The Curse of Spectrum by Paul Gordon

In 2003 Paul Gordon released Spectrum. It was and is a big hit. And, he's made it easier and more convincing with The Curse of Spectrum. Top-quality special cards supplied and online video tutorial. It's a worker and you're gonna use it.

Effect: Four Ace of Spades are convincingly shown to be double-faced. You magically get four blue backs and they change to four different-colored backs.