Help with Behemoth (Normal)

I still haven’t beaten the Behemoth, so embarrassing! Got close only once in the past 5 hours then someone died 3 times in a row. I’m running out patience because each time the team gets worse. I just want some help to finally defeat him.

I use duel blades during fight and always bring life powder and buffing potions (attack and defence potions).

I honestly try my best. I even had a team that kept standing UNDER him and mid map when he targeted them with the tornado.