We all know of this book, it’s a part of the Shadowhunter world in both The Mortal Instruments and The Infernal Devices. And according to Cassandra Clare’s website, it will be released in November of 2013. It will be a guide to the world of Nephilim, and will apparently contain more than 40 runes! If you want to know more check back here as more information is released!
Also, join this Facebook event to talk to other fans about the release!