So, you could dual-wield…
Main hand = Immortal King’s Boulder Breaker
Off-hand = The Furnace
That’s a 400% damage bonus against all mobs, i.e. a 5 times damage multiplier, from the IKBB.
An additional 50% damage bonus against elites, i.e. a 1.5 times damage multiplier.
Combined versus elites = 5 * 1.5 = 7.5 multiplier.
Why would you use the IKBB though?
Put a RoRG in Cube slot 4 and wear two pieces of Aughild’s (e.g. helm + chest)
That’s another 30% damage versus all mobs, and another 30% damage versus elites.
So…
That’s 5 * 1.3 = 6.5 multiplier versus all mobs.
That’s 5 * 1.5 * 1.3 = 9.75 multiplier versus elites.
Then we’ve got a 10,000% on the six piece, so a 101 times multiplier.
So…
That’s 5 * 1.3 * 101 = 656.6 multiplier versus all mobs.
That’s 5 * 1.5 * 1.3 * 101 = 984.75 multiplier versus elites.
But, wait, elites are also mobs so…
656.5 * 984.75 = 646,488.375 multiplier versus elites
Now here’s the interesting suggestion…
Don’t use it with HOTA, use it with WW/Rend. Ambo’s and Lamentation in the Cube.
You’d have BoM for 80% mitigation, along with the ancients for another 50%.
You’d never run out of Fury because of the Ancients, so no Wind Shear needed.
You’d need little to no CDR rolls (due to spending fury constantly with WW, the IK bonuses take care of keeping up WOTB 100%) so could re-purpose those to AD.
I just came up with this off the top of my head in about 10 minutes but as you’re apparently a world class theory-crafter, can you spot why this might be somewhat overpowered, especially as all the damage abilities are calculated from weapon damage, and two-handers have a much higher range than one-handers do?