Yea, but I used a bullshit strategy where I threw all of the enemies on a floating block and stabbed at them for a good 30 minutes while they drained their SP healing themselves.
Then for the actual boss, I had four mages running Braveheart every turn to keep Etna's Atk at 2X, otherwise I couldn't do more than 0 damage. I shouldn't have stood a chance.
I can't repeat the strategy for the next uber boss. There's no floating islands to trap her on
