I too found this easier than I expected. I suspect it could have something to do with the levels of my characters:
Kensai - 13
Minsc - 12
Keldorn - 12
Jaheira, Aerie, Jan - 10 to 12 depending on class.
Probably by this time your party has gleaned a lot of cool weapons and armour so the fight is easier.
I found the fight with the summoned creatures on the first level tougher than the one upstairs!
------------------
"Butt-kicking for goodness!" - Minsc
"Cities always teem with evil and decay. Let's give it a good shake and SEE WHAT FALLS OUT!!" - Minsc
