Got him
my tips are:
1 take improved dodging as reward along the run
2 as ironeye i could stand back enough to see his moveset and actually dodge. don't know how you would see well in melee.
3 get closer to him when he summons the windwall. i was perfectly in the middle of the windwall when it spawned and i instantly died and had to crawl out of the wall.
i did this with 2 randoms and they were impeccable. i got the serpent bow and did my part.
i also have an unbelievably long sequence where marika herself protected me as the boss went into "focus mode" on me, and i literally dodged everything