Mark Elsdon finally releases his incredible 'Four Card Brainwave' effect! Previously shared only with those on his exclusive one day courses, this super-strong version of Max Maven's seminal plot can now be yours! You ask a spectator to imagine four cards in an envelope. They make various choices - every step of the way, they are in control of what happens to the four cards - and amazingly, their chosen card is the only one reversed in the envelope! But there's more! You then reveal that the named card also has a different colored back to the other three! There's still more! You then destroy their minds completely by showing that the other three cards are actually BLANK! The reactions are CRAZY! Perfect 'carry everywhere' mentalism! No gimmicks! Easy to do! 100% examinable!