When my group hit the fourth level, I had nothing but a blank sheet of paper waiting for them. So, the dice got rolled, and it was... werewolves. They killed the one werewolf and then fearfully retreated back to the third level.
So ASE2-3 is done, which means I've got all this free time. Oh wait, the players are heading ever downwards... no rest for me. So let's hash this out.
Fourth level: we've got Hinge-Headed and their Basalt Ziggurat, in a big ol' cave. The Deep Tower runs through it as well, but it's only got some observation windows - no real interaction there. There are Neanderthal slave-quarters arranged in neat rows around the Ziggurat, and palm tree-lined avenues.
The Dark Smokers need some representation too, so I'll have to chuck in those weirdos somewhere. Medusas are 4 HD, and I've left their remains on the 2nd and 3rd levels - well, Medusas are "in". And, Werewolves, as determined by dice.
So interesting factions will be:
a. Hinge-Headed. Their section of the dungeon is largely inside the Ziggurat
b. Neanderthals. Mostly slaves. They are busy excavating more dungeon for the Hinge-Headed - and are just about to break through into a cavern containing a Monolith. Because caveman need monoliths. There is a small group of escapees lurking about as potential allies for the players (or maybe the players will rat them out to the Hinge-Headed in an attempt to curry favor)
c. Medusas. This isn't really a faction, just a nest of them. There will need to be rumors of big Medusa treasure, because otherwise no sane player would go after them. They'll need to get spruced up a bit too, standard Medusae are booooring - they'll be the Gorgona sisters, who constantly eject their stone-gazed daughters to wander the dungeon. They'll have some extra abilities and weirdness above their normal Medusa children.
d. Werewolves. They occupy the area around the secret tomb of the King, and are headquartered in the Jungle Room. They are led by their chief, Warren, and their hair is perfect. There is large chunk of moon rock hanging in an exhibit room - illuminating it with Klieg lights generates enough lunar radiance to turn them into wolfmen. Control of this room is critical to them
e. Dark Smokers. They will have a barter-town sub-level. It will have heavy representation from the lower levels. Dracula's minions (Renfield et al) will be there, among others
f. Rust Monster Lab. HAHAHAHAHAHAHAHA. I'm laughing just thinking about this one
g. Viscous pit-bulls, crawling from the slime pits uncovered by unwise Hinge-Headed excavations (thanks Gusty for the awesome typo)
I need another major faction - the only major forces are Hinge-Headed and Werewolves right now, the Medusas and Dark Smokers are just sideshows.