The PERFECT Halloween Effect! Reveal ANYTHING in the creepiest (and coolest) way! Reveal Thoughts IN BLOOD A card is selected, memorized, and lost in the pack. The magician reveals the wrong card, appearing to have failed miserably. The magician can then use a knife or the card to give himself a cut. When the blood is dripped onto the card, an eerie revelation forms in the liquid. NOTE – Please use extreme care and caution when using knives and stage blood. Adult permission and supervision are strongly recommended. By purchasing this effect, the customer indicates that he/she is over the age of 18.