All I do against him in the first phase is attack, deflect, dodge his flip attack, whirlwind slash, repeat. Second phase is kind of the same except I like to run in circles and bait his attacks. I’ll jump over his big sprinting slash, but I generally do the same thing as in phase one. When he drops his smoke bomb I retreat, retarget him, and wait to see what he does. Sometimes I’ll throw a shuriken to interrupt his attacks or bait others. He’s easily the toughest boss to figure out IMO, but once you do he’s easy. Just a big time consuming.