>https://files.catbox.moe/flc76h.mp4
I am very pleased to say that I take back everything I said about Mystrana and the problem with the three different versions of her that I had borrowed from other players before I ended up getting her myself was 100% on whatever abilities they had given her and not Mystrana herself.
For the most part Okyuu had been able to mostly solo this thing on her own and the problem was just killing both the tentacles at the same time before one of them could heal it, and she still did at least half the work on the Boss alone while also landing the final blow, but Mystrana completely shut down the entire right side of the arena to the point Aether's revive-powerup didn't even kick in for the majority of the fight. Either those Whirlpools are doing a lot more than I thought they were or there's something else I'm unaware of going on but either way I'm pretty impressed.
I had really wanted her to be good, so it makes me glad to finally know she can be. She's just extremely dependent on her subskills is all.

I've grown to enjoy this boss fight too, so I'm glad Okyuu and Co. were finally able to beat it.