Updated 11/12/2015: We had some good suggestions for the group build from some twitch viewers!. It looks like loaded for bear is a better option and we made a good discovery with this build.
Using convention of elements in the cube is a good choice because it rotates from cold immediately into fire. You will spend every element of convention refilling your hatred with elemental arrow with a cluster arrow every three seconds until you hit the cold element and then once it changes into fire you will hold down cluster arrow until it's over. Even without reduced resource costs if you rotate your abilities through convention like this you won't have a problem with hatred at all. This effectively gives a big hit all at once during fire when everything aligns, including wolf activation. We'll be revisiting some better options in place of resource cost tonight on twitch in an attempt to maximize the build.
With the new version of the Manticore it now comes with 75%-100% bonus damage to cluster arrow and 40-50% resource cost reduction to cluster arrow. Right now with no resource cost reduction on rings(unlike what we had planned) we have no problems spamming cluster arrow during our fire element and using it every 3-4 seconds to keep up bastion. Considering this you definitely can not put Manticore in the cube. The cluster arrow bonus is too powerful to pass up. Also since we don;t have a problem with managing our hatred we replace Marked for Death:Mortal Enemy for Grim reaper. This works nicely with the Area of Effect for Cluster Arrow.
We'll be streaming live on twitch doing more testing at 7:00pm PDT Tonight, Friday, Saturday and Sunday.
Stay tuned and I'll keep it up to date as DiabloFans is updated but for now this is designed solely around 2 man Leaderboard pushing paired with a straight DPS.
(WIP while we are waiting for the PTR and more items to be realesed etc.)
Watch me and Cursedsteel test this and many other builds live on the PTR at twitch.tv/midknite !