Pielorinho said:
Same here -- glad we could help!
Daniel
Well I must say that I did it on a whim. I try not to second guess myself too much as a GM, but as yesterday afternoon got late, I thought to myself, "Dammit, this is Hell they're in. It should be special!" The inspiration you guys gave me added tremendously to the story and it's just the kind of thing that makes ENWorld a top-notch community.
Here's basically what happened (I may hedge on a bit of the background details because it is possible that my players will read this and I don't want to give away too much). And, Darklone, you may or may not want to read this depending on how you feel about spoilers for the Story Hour:
The group arrived on a promontory. In one direction lay a forbidding set of crags ("Kind of like Mordor on a bad-weather day.") and in the other was a large plain. On this plain was a white pyramid and there was a "horde" of devils chipping at it with picks and mattocks. The party dithered for a few minutes alternating between saying things like "Crap!!" and "What are we going to do?" and "Crap!!!"
This took long enough that eventually they got buzzed by an invisible Imp. The Imp then led a Hamatula and three Barbezu up onto the promontory to attack them. The devils were talking about having been paid in souls to go attack the pyramid and that this little side adventure was a waste of time. But the Imp assured them that these were "Fresh souls, and not like those puny, cheap ones they'd been paid in to destroy the pyramid." The party tried to hide but flinched and battle ensued.
Despite being somewhat low on resources, the party mopped the floor with these guys and the
24 lemures they summoned (the devils referred to these as the souls they'd been paid in). The party has got very good AC's all around and only a lucky few shots got through their defenses. But they did burn most of their remaining spells and the Druid lost the use of his last Wild Shape when he had to transform back into human form to Heal the Rogue from the Wounding damage inflicted by the Barbezu glaives. The Imp survived and escaped to warn the devil horde below.
The party then noticed that about 50 devils had broken off from attacking the pyramid and were coming up the road in their direction (they were coming from about a mile away so it would take a few minutes to get there - I opted not to let them use their Teleport for similar reasons to those that the party's Teleport landed them there in the first place). The party debated fighting them for a minute (which would have been suicide) but came to their senses and fled down a road into the crags, hoping to hide somewhere and rest.
The road was cobbled with the faces of the damned who watched them pass. They party were afraid the road might "tell on them" so they used a pinch of Dust of Tracelessness and the eyes of the damned glazed over as they passed.
They arrived at the bottom of a desolate valley and found a bridge crossing a river of clear, salty water. The bridge had a sign labeling it the "Bridge of Regret" and the river was made of the tears of the damned (the party never saw the headwaters, but hoo-boy

). Chained to pillars along the bridge were the damned souls of those who had made decisions that led them to damnation and eternal regret. Among them was the great-uncle of the party wizard.
The wizard knew that his uncle had been part of a cult the party was after and had done some questionable things that he preferred remain hidden so he tried to misdirect the party away from the bridge so they didn't get a glimpse of his family dirty laundry. They decided the road was too obvious a path and struck off down the riverbank looking for a place to hide from the pursuing mob of devils.
They got barely out of sight of the road when they encountered a mysterious female voice ("like chocolate covered honey") that spoke directly into their minds (an Erinyes). She told them that she would offer them a place to hide and a bit of information they sought in exchange for a kiss. The party all knew this was a bad idea but (especially after she used a Major Image to reveal what she looked like - The unholy love child of Monica Bellucci and Lucy Liu - I knew that particular combo would be irresistable to the Rogue's player) the Rogue agreed to the deal. The Fighter/Cleric of St. Cuthbert gave him a Protective Ward to "Make him strong in the face of her charms." It worked too.
She took him inside her lair and kissed him, gazing deep into his eyes. But he resisted temptation and secured the party an overnight stay in her lair and some info about the pyramid the devils were attacking. But sleeping in the lairs of diabolical seductresses has its hazards. She kept talking to the Rogue and it became obvious that he wanted more information and more of her. She agreed to tell the party anything she knew about Hell and the way the horde of devils related to their quest in exchange for...well, you know. He went for it.
This time, he didn't have the benefit of the Protective Ward and he found himself whispering promises to her that may well land him a coveted spot on the Bridge of Regret at some point in the unspecified future. He sold his soul. Cheap too.

This put the Erinyes in a very good and very chatty mood and the party got some good information out of her (only fair I suppose considering what it cost them

).
Among this info, she told them about the strange coins that they found on the dead Hamatula and Barbezu. These coins were made of a red-tinged gold and had a picture of a sinister looking fortress on one side and a tormented face on the other. In Abyssal were written the words "Soul Cent". Basically the Lords of Hell kept a large pool of damned souls (in the form of Lemures mostly) in their stables. They then issued currency against the value of these souls for the devils to use for trade amongst themselves. The party deduced that this currency could be used to possibly buy back a soul from the Devil Lords or anybody else who owned one.
At this point the Wizard revealed the situation with his great uncle and informed the party that he would have information about the cult they were hunting. They could use the currency to buy back his soul and he could give them lots of information. They thought this was a dandy idea. After resting they returned to the Bridge of Regret.
The Wizard flashed the money and implied that they might be willing to buy poor Uncle Manilux out of damnation. Uncle Manilux jumped at the chance (well, would have jumped if he hadn't been chained by the wrists to a stone post on the Bridge of Regret for eternity) and spilled his guts about the cult (he actually knew a little less than they thought he did but they still got some solid info here). Then the Wizard backed out of freeing his soul, saying that he never really "promised" that he would free him and that he might come back and do it later. Manilux was incensed, but hey, what's a damned soul chained to the Bridge of Regret to do? Trusting his great nephew was just one more thing that he would have ample time to regret later. (I'm totally sliding the Wizard's character toward the Evil end of the Neutral box for this.)
The one other cool thing that happened at the Bridge was that the party noticed that the shackles on either side of Uncle Manilux were vacant but that names had been chiseled onto the pillars. One was the name of the Wizard's sister who (unbeknownst to him but knownst to the Rogue) had recently married a powerful Senator right after the demise of his previos wife of many years. The other pillar had the name of a nasty NPC the party encountered a LONG time ago (literally a couple of years in real time) and THOUGHT they had killed. "Why isn't he hanging there? Wait a second...where did we leave his head when whe killed him? Oh crap..."
From there they returned to the promontory and promptly Teleported back out of hell the same way they came in: Back into a fairly nasty situation that they desperately tried to escape from in the first place. Sweet!
I'm not sure I've done the session justice but it was awfully fun. The conversation with the Erinyes took up a sizable chunk of the time and was immense fun for me. I loved how the party, especially the Rogue, knew that she was after their souls and knew that she was trying to seduce them, but couldn't bring themselves to just walk away. Great roleplaying by everybody involved.
Thanks once again to the wonderful folks of ENWorld for the inspiration and help. And in particular, the dastardly ideas of pielorinho have me looking forward to meeting him in person here in a few weeks at NCGDIII!