As the title said, what do you expect and think will happen in the fight?
Breaths, cleaves and tail swipes ofcourse. No need to mention those though :P
What do I believe myself? First of all, he is originally the Earth-Warder, so I believe that will have a big part in the fight, not just flames. We will probably see both Earth and Fire elementals along with additional Twilight Cultists.
Well, one thing I can be sure of is that there will be tons of AoE damage :P