However, without the Fury of the Ancient shoulder, I cannot keep my fury up especially when facing rift guardians who do not summon any mobs. I checked Alkaizer's video, he seems to be able to WW non-stop even when facing guardians like the butcher.
Any suggestions on what i could have missed? besides, what is the basic toughness required for GR65? My current toughness is 23m (or 38m after shout) and seems to be as thin as paper in GR 60 with Ancients and Unity.
The butcher is a great boss because you can stand in the pool of fire he puts down and it will feed you Fury. It's a problem for everyone, it's just one you have to manage. Don't forget that most of your damage is done by rend, your whirlwind is comparitively low damage filler.