So, I was exploring outside-the-box options for DPS in deep SR. Here’s a video of me testing a “% Reduction to Enemy’s Health” build in solo SR 210. You’ll have to imagine the panicked screaming in the video, I had my microphone turned off 
Here’s the build used - Witch Hunter, Level 100 (GD 1.1.9.7) - Grim Dawn Build Calculator
