For Hegio specifically there's also the delayed animation when he ults before the actual damage lands, and in that little window the attack buff can get lost so have to take that into account. I also believe Buff Prohibition does not work on either AB or this boss because he dispels all debuffs from himself before putting his own buffs up. So i would suggest using Dane, or Sadie to focus the Def Up buff coz i think you are able to survive through his Att Up buff if he has that when he ults. Def Up buff is what is important to remove (assuming we can survive the entire 5 min), else we will not really hit good numbers.
