My Castle Greyhawk PCs are overdue, in one or two cases, to hit level four, so it's now or never, and I seeded the entry into Zjelwyin Fall in last night's session. I have to figure out exactly how my background changes require me to rework the module (if at all), since the PCs will be acting as agents of the local clergy of Celestian and not looting the tomb, but instead retrieving an item stored there previously by mutual arrangement.
I haven't decided if they'll be charged to either
snag the item (a scroll or book of prophecy or something related) directly, or
wake the lich to donate two objects to him in order to remove their desired object, or
both (with #1 being the plan, and #2 the backup in case they awaken him or he is already awake)
I think that Shodreth Drhachod (I added the "r" to the surname) has this working relationship with Celestian and his clergy, where Celestian helped to fashion and sustain Zjelwyin Fall and in return the lich helps to guard and secure items that he and his clergy wish to remain highly-secure.
Still noodling, but excited to be bringing this adventure to the table if the PCs take the hook (which I think they'll be inclined to do, since it involves the priesthood paying for their current and next-level training costs, or something equivalent)! =)