Alzrius
The EN World kitten
thorian said:There are three sources I can think of off of the top of my head. The planes of law box set, the hellbound: Blood War box set and the Guide to Hell. The primary source of the shakeup is in Guide to Hell, which deals a lot with infernal history.
Faces of Evil: The Fiends doesn't have too too much history in it, but it's still a great product. I like that it explores the whole "ancient Baatorian" thing, that otherwise (Hellbound and Tales From the Infinite Staircase notwithstanding) was ignored.