The last boss of Maw of Souls (Helya) is probably the hardest Legion dungeon boss for 5 BM hunters. The stretched fight with different phases and unavoidable DoT damage makes it very hard not having a healer.

And this is the case, not even counting the issues (bug) in p2, where the pets have Line of sight problems with the boss. And as it looks like, that is still a problem.

For example in this video, it took me well over 15 seconds for my pet to get LoS of the boss. Had I been able to attack the boss as expected, I would have not missed out on a ton of Kill Commands during Bestial Wrath and all my other cools, and she would have been dead within that time. Instead I had to wait for the next BW cycle to finish her off.

Anyway she still died because this was only a mythic level 1, but my well-geared team was almost dead. And she was probably going to submerge soonish, which would have been the end.

Considering I did not use Heroism in this video, this is probably "doable" with less gear/dps, but tbh I would not recommend anyone bothering with this. There is plenty of other mythics with better suitable bosses, that also aren't bugged.