Even its name is a secret. Some say the name comes from the Sodality of Vryn, which identifies thirteen currents of magic and gives each a letter designation. M is the 13th and most powerful. Others, however, say that the title refers to the original writer of the book, while still others say it means mystery, or—perhaps most simply and obviously—magic. Regardless, Book M is a hardcover sourcebook on magic, with new spells, ephemera, artifacts, and much more. Comes with a deck of over 100 new cards!