I recommend an external primer for heat + viral for armor strip + viral dmg multiplier on health (vulpa panzer or crescent, hound, diriga, nautilus, predasite)

viral multiplier at 10 stacks: dmg x4.25.

Mod empty/flex slot: (primed) [Fury], [Magnetic Rush], berserk (all use a V polarity), riven

I don't know what would be the best here but viral, electric, crit dmg, dmg, crit chance, magnetic, corrosive, explosion are all welcome in my opinion. A good negative to have would be heavy attack stuff related since crit chance on slide and range are always neat to have.

[Carving Mantis] has massive damage multiplier on auto attack without moving in a specified direction or blocking while attacking + various forced procs like lift, bleed, slam. (feel free to use a stance you're comfortable too)