Reading the backstory of Jzadirune made me wonder about a small little thing. How did the Grell end up there? Given that there is not any direct passage to the Underdark from Jzadirune (and especially from the northern part of the complex), it stands to reason that the Grell came up from the Malachite Fortress. However, since "...not long after the gnomes left a Grell took residence here...", one could assume that the Fortress was still maned by the dwarves at the time of the Grell's arrival. Thus, I think that it would be reasonable to assume that:
1. the Grell arrived via the Underdark to the Fortress below Jzadirune,
2. managed to navigate/escape the fortress and end up at the elevator,
3. used the elevator to reach room J63 in Jzadirune,
4a. managed to open all locked doors (even though it does not have the ability to do so) between rooms J63 and J36 or,
4b. managed to discover all secret doors (even though it does not have any ranks at the search skill and its Intelligence is a mere 10) between rooms J63 and J36 AND managed to escape the Raggamoffyn at J31 while using this road.
Hmmmm, wouldn't it be easier if there was a direct route between the Underdark and the northern part of Jzadirune? I would suggest a simple mention of a collapsed tunnel (so as to prevent potential further intrusions from the Underdark) probably at the north or the northwest corner of the J27 room. The passageway could lead to area M8 a few hundred meters away from the Malachite Fortress's entrance, and could have been digged by the gnomes prior to their departure using the Automaton in J27 so as to bypass the Fortress. Players navigating Jzadirune would probably not understand the meaning of the collapsed tunnel, but hints could be dropped while they explore the area outside the Malachite Fortress, where they can find the other end of the bypass tunnel.
Let me know what you think!!!
Sounds sensible enough to me...
Of course, depending on how grell's reproduce and all, you could have just as easily explained it as:
A curious gnome bought/found/stole a mysterious orb and couldn't figure out what it was. In time, the orb turned out to be a grell egg, and shortly before it hatched, Jzadirune was abandoned.
But ya know, you're way is much more complex!