If no umbral forma use normal [Vitality] and a rank 5 [Adaptation]. U.Vit, [Fleeting Expertise], Exilus, Aura, & Arcanes are all customizable to what you prefer.
Just dont use armor mods or [Guardian] as they add such little damage reduction to the already 6000+ armor you have from vex. And no damage mods or arcanes on his weapons either for the same reason(Imagine you have a serration-hornet strike-point blank-[Pressure Point] at 820%{this includes Condition Overload}). Fill those slots in with faction mods(Bane of grineer, Expel of Corpus, Smite infested, etc.) or Fire rate/attack speed/reload speed/crit damage mods.
Shared Polarities across all builds