A simple 1 Forma Build that allows us to take [Excalibur Umbra] to an unexpected new level (for me at least) while allowing us to focus purely on damage with his 4.

Note: This heavily relies on Arcane Energize to an unholy degree which I'm not happy about but it is somewhat viable for those who lack this Arcane to use [Hunter Adrenaline] instead of [Augur Secrets]. We lose the 100% status on his [Exalted Umbra Blade] but I was able to keep both Gloom and Umbra Blade running without any real issues.

This build looks like a bit of a mess, I know, but surprisingly it works, giving us a constant healing pool with Gloom because slowing enemies never hurts along with the Str% we need to be able to guarantee the 100% status on his [Exalted Blade]. It is imperative you have Red (or other suitable Fire creating Emissive) to be able to fully exploit how quickly you can maintain health and kill enemies due to armour stripping - I do intend to test with Cold proc for Corpus SP Enemies as they are still problematic due to their general loathing of armour.

To run this effectively it's worth taking a few moments to get your energy up to ~300 at the beginning of the mission then just pop Gloom and Exalted Blade on and watch things die very quickly while your health doesn't shift even a tiny bit - except with Corpus, as I say they still prove problematic on SP for this guy.

Whilst Energize is imperative, Arcane Strike is not. I do however recommend it due to it's attack speed increase which helps us focus more on damage for his Umbral Blade which can be found here.