So I've been testing this build. My Templar is 70 and haven't yet been able to work in leadership and an Aura, but overall it works really great.
My Gear:
This just some stuff I threw together along with a 5-Link Marohi I already had. The Amulet is the only I've bought for the build.
I found linking CWDT - Immortal Call (for big alpha bursts) - Phase Run - Increased Duration to really help the build keep moving in between packs. Just using a perpetual Quicksilver is fairly good as well. I am going to also run Blood Rage when I get my links worked out properly as it will generate Frenzy charges that will allow me to do more damage and keep Phase run up longer.
Some key points about the build:
* This is a proliferation build. Everyone says its dead, I think this build, and other Herald - Proliferation builds breathe some new life into it.
* You do your damage in three concentrically larger areas. First is the Ice Crash's three waves of DPS which should just about kill anything but a Yellow by itself. Then comes the overkill on anything that survived which will do a decent about of damage, and then finally is the Proliferation which will finish off most yellows and kill anything that comes anywhere near you for the next ten seconds or so.
* Bosses are a little bit of a challenge at times. Usually taking 4-5 Ice Crashes. I use Vaal Molten Shell, a Lion's Roar, and that seems to be enough. Though I've been skipping bosses likely to one-shot before I even get an Ice Crash off. You can actually get an occasional good stun against a boss with this build. It seems to have a weird interaction with Lunaris Piety, as you stun her and she sort of hangs for a bit.
* The only real difficulty of the build is finding a good balance of grabbing defensive versus offensive nodes while you level. I wouldn't switch to Avatar of Fire right away. I would make sure to have at least two wheels of Fire Damage nodes before switching. The reason you take Avatar of Fire is purely because you're already scaling Fire Damage. The more you scale Fire Damage, the more Avatar of Fire (AvF) becomes the obvious choice. The Ice Crash cuts your base DPS in half essentially, turning half to Cold damage from Physical. With Avatar of Fire (50%) & Cold to Fire (50%), all your Cold damage is converted to Fire and 50% of your Physical is converted to Fire. This means, depending on how the conversions work, either all of your Physical is converted or 75% is converted. What ever DPS you lose to AvF (in this case I am not sure there is any) is blown away by the fact that the converted damage is increased by your scaled fire damage. Someone asked why take Avatar of Fire in the reddit thread, and so I though I would include an explanation here.
* Added Fire is not as good for this build as you might think, at least not without a Melee Physical Gem in your link setup. It sort of depends on which Aura you run (Hatred or Anger) and what level your Cold to Fire is in comparison to your Added Fire. Both are good.
* Get a Quality HoA and a Quality Elemental Proliferation. The Q-HoA increases global fire damage, and the increased duration of burn is really nice from the Prolif.
The BiS Weapon for this build would probably be a 6-link Axe with a GG Physical Roll, Fire, Cold rolls, and Attack speed.
My 6-link axe would be:
Ice Crash - WED - Fire Pen - Cold to Fire - Melee Physical - Increased AoE
For a 6-link Marohi:
Ice Crash - Wed - Fire Pen - Cold to Fire - Melee Physical - Added Fire
