GrimTools: Dervish, Level 100 (GD 1.2.0.3) - Grim Dawn Build Calculator
This is a rough/first draft attempt at this dual-wield retaliation build. I wanted to make a quick proof of concept, but it worked out pretty well!
Two big ol’ retaliation swords. Lots of big ol’ retaliation items. With 18% retaliation damage added to each Righteous Fervor strike, I believe this affects the attack from each blade, giving you a potential 36% retaliatoin damage on strikes when both blades hit. Execution gets a combined total of 86% retaliation damage on an attack, and the highest Execution hit I’ve seen so far is ~590,000 damage. Not bad for a retaliation build 
It regularly crits for 370k+.
Edit/Update
Just did a second run of SR 75, hit this damage number
The build is reliant on greens for one main thing - Attack damage converted to health. So specifically, seek out rings that can help you heal when you’re hitting.
This build lacks CC resists, and can be killed quickly if frozen, or if it can’t reach it’s enemies (trapped), or if the enemies are highly resistance to lifesteal (Zantarin).
Aside from those circumstances, the build really does quite well for damage.
Enjoy!