Without going into excruciating detail, the party confronted the apparent demon, moved down an Ancient corridor beneath House Ahzenbakh (Tyb in 2D Shadow-form throught the rest of the battle), Ashta fought the unseen baddie in Psychic combat (doing a good chunk of its DP total), the rest fought skeletal mooks, and then were confronted with a fairly wimpy Shorrannin which was slain.
Ashta psych-blasted it one last time and tore through its non-mind only to reveal thousands of its Hive-siblings suddenly looking back at her. Its carcass self-destructed injuring everyone, especially Skelk and Rhur who were not in sealed e-shealth Scout suits, and then the tesseract labyrinth began to collapse in upon itself.
The party not only managed to escape, but saved the KO'd cavorters and pre-sacrificial kids, but lady Miren, with implicit authority from the Governors, killed her sorceress mother, Dame Diem. The Governors asked Miren for (and were granted) permission to take over the mansion so as to better safeguard the site, as it was still extra-dimensionally unstable.
End of that adventure.
Beginning of next adventure:
The Aelbaan Sphere, having been nearly destroyed by fighters launched from the cloaked ship in orbit, had been repairing itself and hadn't been able to assist Ashta since they'd entered the sea cave. It asked to be transported to the Shadow Plane where it wouldn't be fighting gravity to repair its various micro-fissures. Tyb couldn't do it alone and went off in search of assistance, meeting the Shlzm. This group describes an army of human worshippers of a demon-god raiding their underground realm, and secures the aid of the party in exchange for their Shadow-transport of the Sphere.
He also meets a very loony Dryvv woman named Kyllia who is essentially a historical quasi-goddess who offers a number of her handmaidens to accompany Tyb in his future raid of the Aelbaan starship (in exchange for a drop of Ahni's [and by extension, Tyb's] blood). Kyllia is whispering into her slumbering Grand-(or great-grand-)-father's ear about wanting to have possession of (one of) Tyb's timelines. Tyb is given an inky copy of the Myth of Power, the mythified history of the pre-Dryvv, proto-Dryvv, and Dryvv peoples. It can be manifest as a regular tome, or can be 'read' in his mind's eye as a (searchable) running film narrative of the contents.
Ashta, Mela, and Tyb confer and determine that the demon was in fact a psionic delusion/illusion generated by the Shorrannin. And also that the Aelbaan are aware of their possible defeat at the hands of the party, and are moving against them, fearing that Ashta and Tyb will learn to unify their power. This is then vaguely set against the background of the Dryvv' interest in Tyb's timeline, and his metacosmic relation to another character of his from my Pathfinderish off-the-rails game that preceded my running UWoM for them.
The party are now in the Endgame of followers, land holdings, and approaching lord/dameship.
Fight on! :)