If used properly, this setup can absolutely dumpster Steel Path content without ever needing to utilize your passive. It involves synergies between Sevagoth (Build), Kubrow (Build), and any top tier melee weapon, but I prefer my Halikar Wraith (Build). If you're just looking to clear normal Star Chart through Sortie missions, you should check out my Ultimate Fungame Speedgoth AoE Nuke build. And if you're not a fan of the Kubrow requirement, I have another Hardcore Endgame build which eliminates it and focuses on [Sevagoth's Shadow] over his main form.

Note: You shouldn't even need to go into your Exalted Shadow, but if you just want to and need a build for that, here you go.

Survivability - [Umbral Vitality] (boosted with [Umbral Intensify]) gives you a large health pool to start with. [Augur Secrets] gives you a set bonus that will grant you shields every time you cast an ability, and since you'll be spamming abilities, this will allow you to constantly take advantage of shield gating and reduce direct damage to your health. When you do take health damage, you have a chance to proc Arcane [Guardian] and receive +900 bonus armor for 20 seconds, for a total of 1010 armor. Additionally, the Mecha set bonus is maxed out between [Sevagoth] and the Kubrow, meaning that the Kubrow will mark an enemy near you every 15 seconds, and killing that enemy will grant you +60% of your base armor for 20 seconds for every enemy within 30 meters via [Mecha Pulse]. Since you will be pulling enemies into close range constantly, you will have an additional 990 armor if as few as 15 enemies are within 30 meters. This means you should have 2000 armor with near constant uptime, and that number only goes HIGHER the more enemies in your vicinity. As if that wasn't enough, Pillage (requires subsumed [Hildryn] in Helminth) will both restore your shields and grant a large amount of overshields every time you use it to strip enemy armor/shields.

Damage - 249% power strength gives huge burst damage via Reap after Sow has been applied and Pillage has stripped enemy armor/shields. Reap applies the Death's Harvest debuff automatically, so there's no need to switch into Shadow Form. The 175% range ensures you will cover a large AoE with both Sow and Pillage, maximizing their deadliness.

Sustain - 160% efficiency makes Reap cost 10 with Sow and Pillage at 20, meaning you can spam combos pretty much endlessly, so long as 1 in 30 enemies drops an energy orb and procs Arcane Energize.

Why The Melee Weapon? - The weak point of this setup is the Kubrow. Even with as much survivability as mods and Forma can buy, they will constantly be taking a ton of damage. Link Armor allows the Kubrow to benefit from the ridiculous amount of armor [Sevagoth] will have, but [Primed Pack Leader] is the best way to pump health back into the companion whenever inflicting damage with the melee weapon.

How Does The Whole Setup Work? The loop generally goes as follows:

1. move into a bunch of enemies
2. cast Pillage to strip armor/shields and get some overshields
3. cast Sow to prime enemies for damage
4. spam cast Reap to kill affected enemies and fill the Shadow meter (and proc [Mecha Pulse])
5. repeat loop

Don't forget to throw in some melee damage periodically to heal your Kubrow, and have fun destroying the Star Chart!