This e-booklet by Jeff Hinchliffe explores an often overlooked principle in card magic. Exploited by magicians like Charles Jordan and Ted Annemann (and discovered by Conjuring Arts to go back to the late 17th century) this subterfuge is so devious it's hard to imagine it not being more popular. Alas, it's almost as if it's been forgotten.
Jeff has developed a couple of different approaches with this principle, and describes routines with it, as well as giving you a variety of tools to use this principle so that you can develop your own way of exploiting it.
There are tricks in here that will fool your fellow magicians, yet are still simple and direct enough that they play for laymen. It doesn't get any better than that.