The Art of Depravity is an artbook focused on exclusive art and character profiles, giving you a deeper, more insightful look into the characters that build up the world of depravity.
It is currently in its 3rd edition, and features 78 pages of a magazine style book that is best viewed as a book in 2-page view.
It is not sold separately but it goes on special from time to time. Currently it is bundled in with the beta when you sign up for it!
Read more about the beta of the newest version here.
Cheers,
Dante