Modus Pocus: A Journal of Playing Card Problems and Methods was a sporadic, short lived Magic Periodical from Allen Martin in the early 1990s. Three issues were released.
It was designed to focus on Card Problems and methods to solve those problems.
The first issue contained solutions to "The Three of Clubs" problem (from Ed Marlo and Allen Martin). From Greater Magic: "A spectator looks over the faces of a shuffled deck and merely thinks of one. The performer takes the deck, runs through it and puts one card on the table. face down. This proves to be the card the spectator thought of."
It was printed on red paper, most likely to combat xerox copying.