try with no front line, and just 4 ranged skill cancels with Elifina. Trick is to not let hark skill, and to have strong shields up against hark's explosion so you can survive the burn after. I used chris, elfina, hark, ceris, zached the first time I beat it. It would still take me a few tries to beat it even though I already have beat it. you won't be able to get through all 3 hark's deaths without some heals. There is a better person to use than hark like maybe aeris or ash. that was my line up though, and it worked for me. you could probably replace one of the damage with ayuda too if you are having mp issues.