I downed the boss and I figured out the issue.

The meteor phase where you look to the east was never the problem, there was a communication break in my expressing what was killing me. In the latter iterations of the lane selection phase, there is the spread effect that you WILL take, and that was the meteor that was consistently killing me... because I was almost always DOTed by hitting the edges. So once I mastered placement to not hit the edges, I was successful.

Thanks to everyone that added their input. I don't know that I'll grind this dungeon (trust dungeons are just how I level in this game now), but I may get better at it over time because of this initial learning experience!