|"Are you a wizard or not?"
The title of this article is conjectural. Although it is based on canonical information, the actual name is conjecture and may be supplanted at any time by additional information released from canonical sources. If this occurs, please move this page to the appropriate title.
A charge like that of electricity runs through the body of a wizard with this automatic defensive spell.
In 1995, Vernon Dursley tried to hold Harry around the neck, when he felt a sudden charge like electricity running through Harry and he had to drop him. This appears to have been an automatic defensive response on Harry's part, since there is no indication that he intentionally cast a spell.
In 1996, Albus Dumbledore used a similar spell to make Dolores Umbridge let go of Marietta Edgecombe, whom she was shaking violently. This may be a different form of the spell, however, since Dumbledore used his wand to perform it, and it said that Umbridge was waving her hands around like they had been burned.