I'm not happy Bob. Not... happy. Ask me why. Your enemy makes me unhappy, Bob! This drow... she doesn't make any sense. If she has a pathological hatred of deep gnomes, then I'm sure there are places she could have gone to mess with them, rather than skulking around a ruined city for several decades, grubbing for loot. She's just another version of the wight that is presented in Chapter 3 - a weak excuse to have a drow show up.
There just isn't enough rationale for a drow to be obsessed with conquering Blingdenstone (in the case of the wight) or with fucking over the svirfneblin (in the case of Talabrina). I mean - they're GNOMES! Nobody really likes them or thinks they are cool, but by the same token, when have they ever pissed anybody off enough for a 40-year vendetta? It's like an unprovoked nuclear strike against Sweden.
All this went through my mind while I was reading the adventure, but then I came upon Gak Fixen. A "twisted and evil" surface gnome who worships Urlden and plays a mean flute! Ahah, I thought! The Cult of Urlden is just the sort of seriously evil and fucked-up bastards who would get a whole gnome city destroyed, then hang around and just enjoy the wreckage afterwards. Serious Joker-style bastards. Guys who just want to watch the world burn, then roll around in the ashes.
So that got me thinking. If the Cult of Urlden is involved, how are they involved? They've always been involved is the obvious answer. The Cult has always had a presence in Blingdenstone, and now they want to reclaim the city, their ancient temple and maybe kill some folks while they are at it. So for your enjoyment
Appendix 3 Revised - Claws in the Dark.
As presented here, it is fairly likely that the Cult will have a presence in Blingdenstone after the city has been reclaimed from the underdark. I'll follow-up with more information about the Cult, as well as some adventure ideas for after the standard Blingdenstone adventure is finished.