Well, I am using Shion, chaos, and KOS-MOS. When I fought this boss at first I was level 15 for all of them, but now I leveled up to 18 for all of them, and might wait another level or so to take them on. The reason I died at the boss, was because the average damage for the Gargoyle when I killed his minions was ~300-400. I think this was because of shitty equipment, but eh whatever. I was thinking of now killing one of the minions, and then the gargoyle so it doesn't have so much power. I also am planning to attack mainly with KOS-MOS, as I have equipped chaos with Medica-All so he can help heal while fighting.