I've read all the praise for this book, and I also think it's an excellent supplement, but I was wondering how many people out their have actually used the supplement in their games. I'm interested in knowing what parts of the supplement you used (unique lords, new devils, fallen celestials, prestige classes, etc.), how well the parts fit into your campaign, and the player's reactions.
Personally, I plan to use the Pain Mistress soon as part of an attack on a revolutionary camp. She will have tracked the PC's, who are believed to be accompanying a "renegade" erinyes - the target of her attack (the PC's don't know that she is an erinyes, and they are pretty clueless as to the presence of fiendish involvement in the world. That will change soon). The Pain Mistress will be accompanied by either two Osyluth or two Abishai, I'm still undecided as to which. Maybe I'll include one of each, because the Osyluth's dimensional anchor is key to their attack on the erinyes.
Anyway, I expect it will be frightening and challenging for my players. They are only 5th-6th level, so the three devils will pose quite a challenge to the entire camp. I expect the Pain Mistress's Symbol of Pain to be quite effective, and it will be pretty tough for the erinyes to escape her grappling claws.
After that, I'm looking forward to new opportunities to add devils into my game, but I don't see any for quite some time.
So, what are your experiences?
Personally, I plan to use the Pain Mistress soon as part of an attack on a revolutionary camp. She will have tracked the PC's, who are believed to be accompanying a "renegade" erinyes - the target of her attack (the PC's don't know that she is an erinyes, and they are pretty clueless as to the presence of fiendish involvement in the world. That will change soon). The Pain Mistress will be accompanied by either two Osyluth or two Abishai, I'm still undecided as to which. Maybe I'll include one of each, because the Osyluth's dimensional anchor is key to their attack on the erinyes.
Anyway, I expect it will be frightening and challenging for my players. They are only 5th-6th level, so the three devils will pose quite a challenge to the entire camp. I expect the Pain Mistress's Symbol of Pain to be quite effective, and it will be pretty tough for the erinyes to escape her grappling claws.
After that, I'm looking forward to new opportunities to add devils into my game, but I don't see any for quite some time.

So, what are your experiences?