Wikipedia
Zorachus
Zorachus is a fantasy novel written by Mark E. Rogers, a science fiction and fantasy author. It was first published by Ace Books in December 1986.
Zorachus is set in a fantasy world with some similarities to Renaissance-era Europe on Earth, but with significant differences. These differences include the existence of actual magic and the interference of otherworldly beings such as demons and spirits. The world of Zorachus is made noticeably darker by the ambitions of an evil spiritual entity (similar to the Christian Devil) called Tchernobog.