I would say yes, definitely possible, scrolls are a big help.
If you have a dimensional door spell, even on a scroll, the first phase is a cake walk. Just take a second character to free Dame Aylin who then does some big damage in the second phase. Failing that, misty step will get you most of the way there. The first phase we were able to defeat Ketheric without Dame Aylin even having a turn, despite being free, so I suspect that she will help a lot there too.
