She died when the boss was at about 1/10th HP, without her I would have had trouble since her debuff helps a lot.
I had Chaos Magic (nullify 1 enemy buff) as my ex skill... lol. The only buff that Ragnarok Quet seems to use is def up, thought she might of had atk up so took it just in case. Would just call for help if I couldn't do it but she didn't seem to have any atk ups. So I could have probably used something else, though the fight would have just dragged on a bit longer.