OK, I guess I'm done.
After taking a break from the normal progression to work in the arena for several months, i decided to try to finish the map. Been spending gems and spell liberally to get to the end. But boss level 900 has done me in. I have spent countless tries, and countless gems trying to win, but not only have I not, I have not even laid a finger on the boss. I have no clue. And I'm pissed that I have spent so much time, effort, and money on this game only to be left hanging. So disappointing.