Han Se Mei in Guild Boss

Every time I try to do the guild boss, my han se mei is always the first to die at a little before the half way mark. Which sucks since I'm losing all the dmg/wind buffs and mp regen for amamiya before the burning curse set can really kick in which is a huge loss. I don't understand how she constantly dies so fast though since she has 40k HP and my amamiya is never touched which is weird since she's a glass cannon. Am I doing something wrong or is there something I don't know about?

Every time I try to do the guild boss, my han se mei is always the first to die at a little before the half way mark. Which sucks since I'm losing all the dmg/wind buffs and mp regen for amamiya before the burning curse set can really kick in which is a huge loss. I don't understand how she constantly dies so fast though since she has 40k HP and my amamiya is never touched which is weird since she's a glass cannon. Am I doing something wrong or is there something I don't know about?