5.1 MSQ fight

Date & Time: Oct 30 afternoon and evening
Frequency: Always
World name: Hyperion
Character name: ElleVie

Monster name: Arch Ultima
Class/Level: Estinien / 80
Party or solo: solo
Playing on PS4

https://www.youtube.com/watch?v=olh-Vu0TYa0

When I try that fight on Very easy mode, all the bits blow up and I receive damage from all of them and die immediately. Apparently others have the same problem. See the comments below the above referenced video.
"snaplash
No idea how you did this. I used very easy mode, remapped the pet bar to some keys so I could move and fight at the same time, Avoided all the AOE's, but almost always die before the star pattern thing, or soon after. Somehow, you did it with hardly any health loss. I'm about to give up on completing the MSQ."

The player in video took little damage from the bits exploding. I have yet to complete this quest.

Did you use Horrid Roar as soon as the bits spawn? Should kill them all at once.

Also, spamming Als Mhorn was a good health regen.