lol, I was wondering about that too. I was grinding in the mojcado (or something) castle against some low level jhanas and when I crossed a door... BANG... that eye of damnation was right there. I was caught unprepared for battle and lost a good hour of grinding so I never attempted to fight it again. I will try when I'm done with all my sidequests.
Im just worried that he wont ever show up again, some of the rare boss mobs have insanely low spawn rates from what I hear. That being said, 2 omni strikes and full art attacks with 3 teams of 4 and he still isnt even flashing...i dont think i stand a chance in hell at my level *30 something*
I just ran into the eye of damnation and My battle rank is 39. Killed him by luck with emmy as my only party left. I kept using hundred flowers and by chance kept dodging his attacks. Let me tell you, it took fifteen minutes for me to beat him but it can be done.