Ahead of us are a large Mefit, some smaller mefits, and several fire elementals.
Nesbit approaches the guardian of the portal, who informs him that "there is a toll."   The portal burbles a bit, and the guardian says "Uh, stay there."

From the portal emerges a bearded devil and a Erynes (Female devil; like a succubus but devilish).  Bearded Devil glaive causes infernal wounds (resistant to healing) and diseases with claw and beard.    The devils pay the mefits in some form of items; including two books.

The Mefit spills the beans that his master was a servant of Weijass - he had a purple tower.  The Mefit took a bunch of stuff on his way out, but there was more to be had.  We agree to bring back 10,000 gp worth of books in exchange for passage now.  We stride through the molten lava and come out in the volcano.  It's friggin hot here, in ghenna.  The plane itself stands in our way; non-lawful and non-evil characters suffer -2 (for each)

As we journey down the mountain, we encounter hellcats.  Other than being invisible in full light (20% concealment here).  DR5/good.  Resistenance to fire.  Smart creatures, telepathically communicate.  large, 900 lbs, do not have reach.

We spend time observing the city (the halls of enlightenment) and determine we can sneak our way to the purple tower, and hopefully beyond into the main complex.  It will be a complex skill check.  We spend the night on the mountainside; fight off some fiending dire mountain rams, and successfully rest up for the AM.  We set out for the town.