I wanted to give this particular dungeon a try as a healer before actually commenting in this thread, since I didn't understand why there were so many complaints against the Mist Dragon in general. So I did, as an AST with my gear level sitting at 346 when I queued into it. Personally, I think this is where difficulty should have been started, beginning with Kugane/Temple of the Fist. My personal run through the DF (and I will note, my other three party members were random) wasn't too bad: it required a tad bit more healing than what I was used to in dungeons, but nothing that screams at me approaching 'hard' difficulty. So my thoughts that I made in my other thread still stand - the Burn is honestly not that difficult, even as a healer as long you know how to decently play your job well enough.

Even in events where two party members die (which happened to me) due to the double 8-directional AOEs, and then eating a Rime Wealth after, I feel that at this point, all three healer roles have enough tools to still keep the last remaining member alive (like a BLM in my situation) while slowly raising the other two party members. Though I am happy to hear that OP has given it another run and found it a bit better than their original post suggested, I feel like there are still too many players who are trying to fight this level of "difficulty", when this is generally where it should've been immediately after fighting Shinryu.