The Warhammer Age of Sigmar Order Battletome Sylvaneth is a hardcover book written in English by Games Workshop. It focuses on the Sylvaneth faction in the Warhammer Age of Sigmar tabletop game, providing players with in-depth information, rules, and lore to enhance their gameplay experience. As a product of Games Workshop, the book is designed to be a valuable resource for fans and players looking to master their strategy and tactics on the battlefield.