I can't seem to oneshot the boss at ultimate yet with my shia team, is there a berserk mechanic where in the end the boss does the move that tries to absorb four mob and do a full arena attack at around 5 bars of hp left? I couldn't clear the mobs in time and then got killed from that area wide attack.
Also not surprised how much more dmg shia does than my chitose at the same investment level.