From the back of the book:
DEMON MAGIC is the second companion for Stormbringer®, the roleplaying game of action and adventure in the Young Kingdoms.
Authorized by fantasy author Michael Moorcock, DEMON MAGIC includes all necessary statistics, maps, and plans, and contains many original illustrations. Among its contents are:
The Velvet Circle: a scenario in seven chapters, which takes many sessions of play to conclude. The adventure includes a complete red-light district, with business notes and a plan of the Circle.
Sorcerer's Isle: a shorter, more intense scenario to fill one or two evenings.
Runes of Rathdor: analyzes and describes the properties of six magical runes discovered during the reign of the 42nd Emperor of Melnibone.
Sanity for Stormbringer®: introduces the optional characteristic of SAN into Young Kingdoms play.
Six new creatures, six nationalities, seven new Demon abilities, and five new magic items.
User summary:
Demon Magic combines two large adventures with an assortment of new creatures, spells, and magic items. It also includes a version of Chaosium's SANITY rules for use in Stormbringer.