This is how the trick is played- The Tantric applies the foam of soap on his right hand and lets it completely dry up so that there is no trace of the soap foam left on his hand. After this, the Tantric meets the person who has some or the other black magic or paranormal problem and has come to seek his help in resolving that problem.
The Tantric then takes some Red Vermillion Powder in his left hand and chants some Mantra or Voodoo Spell. He then, sprinkles some water on his right hand, takes the Red Vermillion Powder in his right hand, and rubs the Red Vermillion Powder. The Red Vermillion Powder turns Charcoal Black before the eyes of the unsuspecting victim.
The Tantric, then tells the person who is seeking paranormal help that his most powerful Voodoo Spell has destroyed the Black magic and resolved the paranormal problem. This is a very popular trick amongst the fake Tantric community in India, it is most simple trick, which gives amazing results in making the unsuspecting victim believe that he has been witness to a miraculous paranormal event.
Another simple trick used by Tantrics to fool people is to apply soap foam on the right hand and draw figures of Dolls or any other mystical or religious symbols on the hand with a pointed stick and then let it dry. Then in the same manner as in done in the magic trick described above, the Tantric rubs Kumkum on the hand and Black Colored Dolls or Mystical Symbols appear magically on the hand.