Attacking the party makes sense, but it can't get down the tunnel and I suspect my PCs will try to hit from range. So it might start heading up (as per "Tactics"). That will scare them too!
If he doesn't release it (say they charm him somehow before killing him), I wonder how if there's any way for Raknian to not notice that Bozal is dead - "Hmm, haven't heard from Bozal for a few days, and we *do* have a big moment coming up...he said not to disturb him while he did the ritual, and I hate going down into that charnel house...but still, it would really suck if that ulgurstata doesn't show up at the right moment"
If he doesn't release it (say they charm him somehow before killing him), I wonder how if there's any way for Raknian to not notice that Bozal is dead - "Hmm, haven't heard from Bozal for a few days, and we *do* have a big moment coming up...he said not to disturb him while he did the ritual, and I hate going down into that charnel house...but still, it would really suck if that ulgurstata doesn't show up at the right moment"