Igor sacrificed the entirety of his arm, compressed the mass that made up the arm including the spiritual aspect of the arm and used it to open a miniature black hole a perfect replica of its true form in reality. Although it sounded like something a wizard do it was actually sound extraordinary science, according to the theory of relativity any massive object distorts the surrounding space-time around it, based on this theory by creating a mini black hole of such immense mass for just a second caused a distortion of the space-time around Igor and Layton who was close to him.
A temporary creation of such mass and density was difficult to control even for Igor thus it was necessary that the mass be made up of his own body which would help alleviate the difficulty in controlling the black hole even if it only emerged for a split second.