His attacks on his first phase are really hard to track. It took me a minute to master his first phase, he can combo kill you quickly, his grab attacks are all but one-shot fatal, and a lot of his attack chains are varied, so if I managed to get a couple of whacks in the last time he did a certain move, the next time he extends the combo and pummels me.

My strategy of first phase has become to hit him with oil, flame vent him, imbue my weapon with flame and just bully him with it until he recovers. Rinse and repeat. A bit of a safe strat, but it def makes 1st phase much quicker while not exposing yourself to much danger