Here's a thought--Fastilbras did the whole Goetic thing to try to purify himself, right? Maybe he came up short--maybe the Soul Gem encounter should involve completing that purification somehow. And maybe his body won't come back--it could be that this means giving up the things of the world (like a physical body). He could live on as either a ghost/spirit, or maybe even become some higher sort of supernatural being.
I love this idea!
When we pick this back up there's going to be 4 rooms leading up to the Soul Gem. A lot of it is going to be old school "figure out the trick of this room to proceed (safely)."
There's a ghostly reenactment and the ghosts can't be killed by normal means, their leader needs to be talked into realizing he's dead. Very Planescape Torment inspired. Further complication is that ghost leader and an NPC mage apprentice adventuring with PCs are rivals.
There's an angel in a circle who promises help. Hint: it's a trap! The words of binding need to be reinvoked. No religious types in the party, so should be a quick encounter.
There's 77 infernal bronze ewers with an Erinyes temptress who tries to cut a deal with PCs to abandon quest in exchange for considerable material power. Certain players will be leaned on
There's a puzzle to dispelling her, but if she is outright killed she'll just remanifest at a later adventure.
There's a dark grimoire floating in an MC Escher-esque room which reveals terrible secrets. Not sure how I'll run this one yet, but in the dungeon below the Ghost Tower I seeded hints that one of Fastilbras the Mage's apprentices had consulted it. Maybe the NPC adventuring with PCs?
Finally there's the Soul Gem. Besides being a dangerous hazard in itself (which the PCs can't just destroy since Fastilbras is trapped within), the gem is also a puzzle which requires a PC to touch it and "go inside" to retrieve Fastilbras' soul...like a psychopomps journey of sorts. While that's going on then one of the power-seekers the PCs met so far (the NPC Mage apprentice, the Angel, or the Erinyes...depending on which is alive & free) attacks, intending to take the Soul Gem for themself. For the PC psychopomps, I'm thinking they've got to apply the lessons of the 4 previous rooms to get Fastilbras to let go of his guilt / thirst for revenge and transcend to the next stage. What that ends up being will depend on the PCs' approach.
At least, that's the outline I've got for our next adventure.
