Secrets of Light & Shadows
The Secrets of Light and Shadows is the title of a book of magic by Van Nyborg. When spoken aloud in a ritual it opens a nexus into the Shadow Dimension that will pull the chanter into it. James Mandarin, a woefully inept Novice who tried to become Doctor Strange's apprentice, performed this ritual, was pulled through the dimensional aperture and had to be rescued by the good Doctor.