Hello,
With Update 50's change to Empower Damage Done to Monsters being changed from multiplicative to additive, it was quickly discovered that this was a massive nerf for heavy attack builds, with the nerf being more impactful the more damage done bonuses were stacked.
After the summary last week indicating Empower would be buffed to 100%, it looks like the "break-even" point with damage done/damage done to monsters bonuses for a u49 heavy attack build to do the same damage as a u50 heavy attack build is ~43% (slightly less).
For reference, with the Oakensoul mythic and build-appropriate champion points, you hit 38%. Coupled with Energized from Storm Calling, which is frequently run by these setups, you hit 41%. So technically a 1-2% buff for those builds where no other damage done sources exist. If there is any other source, it is immediately a nerf.
The bigger issue here is for heavy attack builds that play in groups or using Rakkhat's Voidmantle. For reference, Rakkhat's Voidmantle currently buffs damage done to monsters by 50% with light and heavy attacks. In update 50, this setup will be pretty heavily nerfed, since it alone is over the ~43% threshold. When you account for a properly kitted out build, the damage done is actually about 93% in bonuses - Voidmantle (50) + Minor Berserk (5) + Minor Slayer (5) + Energized (5) + Weapons Expert (20) + Deadly Aim (8). When used in a trial group, there are a few other bonuses that come into play, that goes up another 20% from Major Slayer & Berserk.
With those numbers, Empower would need to be ~150% or higher for those builds just to break even with how they perform in Update 49. However, increasing Empower to 150% also disproportionately buffs builds that do not stack those buffs, so I do not think this is necessarily a suitable solution.
An idea I saw mentioned would be increasing the bonus from Rakkhat to double further against monsters, to 100%, up from 50%. This would help bridge the power gap from update 49 to update 50 after the math adjustment, and allow Oakensoul players to retain their relative power (with a slight buff for most non-trial situations).
I don't believe nerfing Rakkhat's Voidmantle builds was intentional, but if it was, it would be much appreciated to have some communication on the subject. Otherwise, please consider options to balance the power so that Voidmantle users are not left out in the cold with the Empower changes.