This build is the definition of excess. This was born from a personal challenge push into 20+ rounds of Kuva Disruption solo. This is my non-Disruption variant of the build, but it is still perfectly capable of sleeping its way through Steel Path and beyond.

Now onto how the build works!

Exist.

No seriously, the armor from [Umbral Fiber] and Arcane [Guardian] on their own minimize the damage received in most missions. Arcane Grace will keep you topped off while you and your Wuclone slaughter anything that would seek to end you. Only once you end up in an Arbitration or a long endurance run do you really need to start putting in a little work. There's quite a few moving parts once things get going, so I'll explain with an example. The following is over a period of 10 seconds real time.

Let me set the scene:

It's round 15 of Disruption on Sedna. Ahead of you is a horde of Grineer, and they're all gunning for you. You Cloudwalker straight into the fray, bringing you to full HP. You begin priming up the Nox leading the pack with a quick burst of your trusty [Kuva Nukor]*. Quickly transitioning to your [Gram Prime], ([Vigorous Swap] kicks in) you begin hacking away at the brute in front of you (thanks Naramon tree for the 12x combo!).** You glance up at your HP, 800 left.

The Nox is still standing, but all of that damage you've taken has maxed out your energy thanks to [Hunter Adrenaline], so you activate Defy for the 1500 armor boost. This gives you a good buffer of damage resistance to let [Adaptation] build up.

But oh no! The Nox has attempted a knockdown as you exit Defy, but thankfully you shrug if off with [Primed Sure Footed]. Grace (and [Guardian]!) keep you in the fight, and you fell the monster with a few more chops.

Turning to face the rest of the horde, you see that your Wuclone wingman has decimated most of the crowd at this point. The few remaining stragglers are suffering from multiple status effects (yay [Nukor]!) and are ready to be mopped up in a couple swings of your Gram. Once this group is down, you Cloudwalk over to the next one and continue the massacre.
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Now, I don't actually expect anyone to want to invest two Umbral Forma into a single Frame. As I stated in the beginning, this build is very excessive.

If you're a newer player you can swap the Umbral mods out of this build with their normal variants. [Primed Sure Footed] can be swapped for [Handspring] or dropped entirely, and [Adaptation] can be swapped for [Narrow Minded]. The Arcanes aren't needed for most content, as you still can rely on Defy and Cloudwalker for armor and heals. Aura is personal preference, and [Vigorous Swap] can be used as a flex slot to make up for whatever you're lacking.

In closing, this whole build is overkill, but I hope it inspires others to push their favorite Frames to their limits and to take into consideration the full range of synergies Warframe has to offer.

TL;DR
Be passively immortal for 99% of content, while simultaneously dishing out insane damage with a [Condition Overload] melee, and a [Kuva Nukor] Wuclone, only breaking a sweat in extreme enemy levels.

* Honorable mention to [Helios] and its [Deconstructor] for providing additional crit chance via the Gladiator set bonus