I think Pandaemonium will be about Lahabrea's backstory and lingering plots, not him coming back to life to menace us again after 6.0 being the capstone to the Ascian story. Lahabrea is interesting because when we face him in ARR he's sort of a boilerplate maniacal and enigmatic dark sorcerer boss character and by the time he gets iced by King Thordan in HW its apparent the plot had moved past his kind of character, but with the backfill we had from Elidibus, Emet-Selch, and the knowledge of Amaurot and the Convocation, Lahabrea was given much more pathos post-demise than his earlier appearance would lead us to believe.

Pandaemonium might just be their attempt to reconcile the "maniacal evil sorcerer" with the more nuanced characterization we've had in the recent expansions to give a clearer idea how this man was held in such high esteem by these figures.