Eiyuden Chronicle: Rising

Easiest way to beat this boss if you are over level 40 is to use Garoo and stand as far right as you can and keep swinging away at the boss until it dies. You will take a bit a damage so using Ice runes on your defense would work.

I tested this after beating him on hard mode at level 49 with max armor and weapon and a ice rune level 1 on defense as well as a critical mastery accessory and it took me like 3 minutes to kill him. I got hit a couple of times for about 200ish damage each time. As long as you avoid the falling flaming rocks you should be good.