From the back cover: A range of monsters with game characteristics and evocative artwork. Call of Cthulhu Keeper Decks are designed to provide in game resources, handy references, and information. Use the Malleus Monstrorum Deck when you need to reference a monster profile and when designing scenarios and encounters. These decks provide new layers to plots, enhance the story, and provide quick access to an array of fiendish foes. Other decks in the series include: The Curious Characters Deck, The Phobia Deck, The Unfortunate Events Deck, and The Weapons and Artifacts Deck.