Niftypedia

One of the most sinister objects in Sluggy Freelance, the Book of E-Ville first appeared as a joke, when Riff used it to summon a demon to get him a case of beer [1]. Unbeknownst to him, once a demon completes the task it has been summoned for, it is free to wreak havoc upon the Earth. Catastrophe was avoided that time because the demon could not meet the conditions that Riff set, but the Book remained a disaster waiting to happen. It finally happened when Gwynn discovered the Book and began learning black magic from it [2]. She summoned the demon K'Z'K the Vowelless to kill Riff. She did not know that K'Z'K would possess the body of the person who summoned him; nor that K'Z'K was prophesied to destroy the world. Gwynn has since tried several times to stop using magic, but she cannot sever her connection with the Book. In Shadow Boxing, she discovers that her name is written inside the cover; in Most Wonderful Time... it physically resists her attempts to throw it away. During Kesandru's Well, the Book mentally contacts her and tells her that it loves her. Symbols associated with the Book of E-Ville include diamonds and Kwi birds.

See also Book of Güd.