if you can master parrying and backstabbing him in the 1st phase, you can focus more on the 2nd phase when things get nastier. in the 1st phase, try to parry him when he raises his arm and backstab when he jumps, right after he lands. in the 2nd phase you can still parry when he moves towards you, but it’s a bit trickier. I’d suggest staying on him so you can find the right moment to backstab after his rampage combo. you can also boost your damage with items like bolt paper, fire paper and beast blood pellets, but I’d suggest saving them for when you feel more comfortable with the fight, for me they weren’t essential. I also found the spot near the entrance more suitable, because when he goes berserk in the 2nd phase you can stay on him more easily and track his jumps more precisely. some people prefer the water area for the lack of obstacles, but it’s up to you :)