[Note: This effect was already part of Mentalism Games
From the audience point of view, this effect will look completely improvised as you present it with nothing. Just their fingers and yours. It really blows people's minds (laymen and magicians alike).
Finger burn: Ask a spectator to show you any finger; and put it over a candlelight or an invisible lighter. Your same finger will carry a blister even though your hands were apparently in full view all the time.
Voodoo finger: A variation to give away your business card.
1st edition 2015, 13 pages.
word count: 2621 which is equivalent to 10 standard pages of text