We cleared Hard Mode a couple hours ago and found that the Solo gaze strat on Golgoroth works great still. You may have to do one more round due to Golgoroth having more health but the only added mechanic is some one will get a debuff that is like a time bomb. Their screen will flash and once the time goes down it will do an aoe dmg to everything around you this can damage your allies and it can even be used to damage Golgoroth himself. Hope this guide helps it's still the normal but works great!