 It was the fourth book in the "Dungeon Master's Guide Rules" series that was created for the second edition of "AD&D".The purpose of the book is to detail non-human deities, which, to that point, had not been described for this edition of "AD&D".As author Shannon Applecline points out, "Though the book is putatively a 'monster' mythology, it actually contains deities for demihumans, humanoids, and monsters alike."