Well, I would like to open the two closed cells wich are in the temple ruins (quest of the Umar Hills) but I can't !! I thought they would be opened after killing the priest of shadows (don't know is real name but I suppose (I hope !) you know what I'm talking about...

)but they're still closed. Help me !
(I suppose Mazzy and her friends are in ?)
Another thing in this area, is it possible to kill the black dragon or is it too strong for me ? My party members are around the 12th level and I got some cool equipment...just say yes or no (cause I don't want to spend hours trying to do something impossible !), but don't tell me how to do !