Orator is an easy fight but the only reason you do him is for bards who cant get thaz gloves and since everyone and their mum can kill koltar there is no reason
Prior to the change to prevent dispells, it is still entirely doable and its not in anyway too hard. You simply cant cheese it anymore by having 3 bards and completely ignore any form of a strat.
I sometimes forget that fights involving critical thinking are hard and impossible sorry.
if u check the parser since the cant be dispell'd change happened you'll notice there is a max range now on the debuff..
the fight is still easy, u prob just need to rework your strat.