Volcano + City + 800 years = what's left?

[MarkB]

One option is to give the demons a reason to stay. Maybe a group of the more powerful ones in the buried centre of the city were able to carve out a protective bubble for themselves in the lava, along with some innocent civilians, and in the intervening years have made it their own personal little hell, magically maintaining the citizens, torturing them by repeatedly letting them burn almost to death and then restoring them.

PCs who explore the city think they hear tortured wails and assume it's either their imagination or some lingering ghosts, but if they follow the sounds to their source, they can break into the bubble and attempt to free the trapped people, even if only to let them finally die and pass on to the afterlife.

 

[Bohandas]

Some porcelains require over 3270 f to melt. Lava is between 1800 and 2190 f. Clay pottery melts at around 2300 f. Lots of things can survive lava. Getting them out is the problem

I'd be more concerned about the sudden heat causing it to shatter

 

[tomBitonti]

Say, the demons that arrived through a portal: Perhaps a physical ring (ala stargate) or an outline, with enabling components at key points. The lava was intended to destroy the key components, but demons and cultists were able to scatter them in time. Many of the demons fled or were destroyed. Others are able to remain on the material plane only in close proximity to the components. Others are specifically tasked with guarding the components. The components are in places in the buried city which were protected from the lava flow.

The demons must remain close to the components, either because they are bound to the components, or because they would become unstable and return to the abyss if they travel to far away.

Many of the demons have found a niche in the lava field to slumber. Others watch restlessly from their hidden chambers. The demons are disorganized and have varied agendas: Some want their component moved to a richer location, such as a well populated city. Others would rather just slumber away. A number of them seek to re-assemble the components -- which would reopen the gate. But of course, each wants to be the one who reopens the gate, since that decides where in the abyss the other end opens, and because reopening the gate would garner favor and empowerment. And still others, while clever, just want to slaughter folks.

Mixed in would be the remnants of cultists and of worshipers of the fire god, each reawakening to activity as they learn that the city is being disturbed. Perhaps there are just ancient records, clues to be found by the players to help them understand the history of the city, and the problem of the demons.

Also trapped in the city could be fire creatures of various sorts. Most simply hostile, but others willing to communicate or at least give ominous warnings.

Buried treasure could include weapons and magic items used by cultists, by city folk who fought against the demons, and by worshipers of the fire goddess. This would be in addition to hardy valuable items which would have survived.

Thx!
TomB