This boss on easy (and maybe hard) needs a serious nerf and/or rework.  The fact that even on easy cursed city the best way to beat this thing is just to cheese it with numerous max hp champs, or geogrid with 4 ally attackers is proof enough to me that Amius is a badly designed boss.

I shouldn't have to regear my champs out of reflex and redo their masteries every month just to account for this boss and his 2nd from and then waste resources to reset them back to their regular gear.

I would hate to ascribe to malice what could adequately be explained as incompetence but now that I reread the sentence before I'm not entrirely unconvinced that the boss was designed this way to force players to spend resources on regearing and redoing masteries therefore forcing them to spend more money.