I'll try asking Balthazar's corpse if he's willing to talk.
But I do know if you let Balthazar know you read his diary he says he designed the soul cage and it represents the pinacle of his powers. One of Kethric's notes says that Balthazar has said Myrkul has can bring back Isobel.
But I am hoping the spell works - I wanted more of J.K. Simmons' voice.
(although devs - as much as I like this voice actor he looks nothing like an elf. In fact, if you wanted an example of "not at all like an elf" you would choose Simmons. You should have made Kethric a human)
It still doesn't make sense if the Soul Cage post-dates Ketheric's turn to Shar. That presupposes that Aylin spent 100 years twiddling her thumbs in the Shadowfell, not being tortured by being Ketheric's source of immortality (and thus the point of redirect for his wounds), and that Shar was cool with her apparent ex-Selunite puppet leaving her for Myrkul and sending his chief architect (and Myrkulite) to the Shadowfell, her domain, to Soul Cage Aylin while still leaving the most vulnerable part of his plan within the realm of the very god he abandoned.
I've decided there is one way the plot works perfectly. If you accept that stupidity is a congenital trait in the Thorm family, it explains:
-The Sharran Temple under a Selunite Village
-The mini-bosses in the town being dumb
-Ketheric's behavior and decision-making
-Isobel's selective memory and decision-making
Or maybe the Shadow-Curse also causes brain damage regardless of whether or not you are immune.
