Immort: The good guys have taken heed of the actions. Billy still has his spellcasting ability because of that fact. The reason Billy still has a few weeks before he is demanded in hell is also because of that. It is quite possible that their actions between now and then will result in more direct intervention. However, if there is any god that is more of a believer in standing on your own two feet then Heironious, I'm not sure who it is.
The problem with "devil huntin' time" is that you cannot solve your problem that way. The party certainly isn't going to kill Asmodeus in his lair. And if they die in the attempt then Acererak manages to make himself one with the negative material plane, thus becoming uite possibly the most powerful being in the omniverse.
And besides, Billy has already learned once that being deda doesn't protect you from evil. The first time he died he was resurrected by an evil dragon he had tormented. He was held captive and tortured for 12 years after that.
JERAndall: Well, the fight with the Lord High Exultant went pretty fast. Oskar being a high level dwarven defener was nearly impossible to hurt. The life drain was doing an average of 5 points per round, and The LHE couldn't beat his AC after all of the buffs he had on. Granted, Oskar would have eventually died to the life drain, but it would have taken a few hours of rolling real time.
The vestige never showed up unil they went to its tower. There were chances for it to, but they never happened.
Greybar: Well, all you need for him to do is roll a one. When you're full attacking at 4 attacks per rond, that will happen after five rounds or so. And the LHE was only healing 10-15 points per round, so there was no way he was getting back up any time soon.
I wholeheartedly agree with the idea that having someone else save your butt sucks though. Had the party continued climbing Mount Celestia, it would have happened, but that wouldn't have been nearly as satisfying (IMO) as getting themselves out of the jam.