I've seen this around a lot, and before any of the scenes were shot from the recent Hobbit movies.
Agreed, it does look like it could have been Dol Guldur, but I'm pretty sure it's just a fantasy art. Might even be a Digital Blasphemy piece or a book cover.
Stretching it to interpret the deer as Radagast, in my opinion. I don't recall him ever being a shapechanger, and from the original books he is barely mentioned & never met. He only appears in the movies ... of which I am glad, actually. Generally I don't appreciate the liberties taken with some movies over the original books, but featuring Radagast was both entertaining and helped flesh out & convey several plot elements. So, I'm more forgiving of that than some of the other liberties that were taken. *cough*elf-dwarf-love*cough*