Greetings!
A new question: in your games, how often did the characters confront arch-devils and demon lords (if at all)? Were they successful in slaying these great evil powers, or did such a fight always mean irrevocable, painful death?
For example, did they come blow to blow with Zuggtmoy, did they spell an end to Lolth (maybe in a different way from Queen of the Demonweb Pits?), or was Kerzit's defeat an isolated event?
Plus: was demonkind limited to the base types found in the Monster Manual, or did you invent multiple demon variants to entertain and terrify the adventurers?