You have to get this book because it talks about every type of monster, creature, angel, and demon showcased in the 5 seasons of the show. Even rules on how to play such monsters.
However, the pdf sucks to read. It takes a good 30 seconds on a new laptop to go from page to page, and I am unable to print pages from it due to how many layers it has (the printer wont stop attempting to flatten it).
So, while I love the information this pdf has, it has little use for me in game because it takes too long to pull up a page and I can not print it. I would return it if I could, or they should put out a non-pictured formatted pdf so that people can actually peruse the pdf and print it. Until then, don't buy it.
[1 of 5 Stars!]