Disclaimer: This is based on builds like THeMooN85's and --.Ravakahr.nVbs.--'s. Please check their builds out, and I hope you find my take interesting :)
Swaps:
- Physique -> Corrosive Projection
- Primed Sure Footed -> Sure Footed (if you lack Primed)
- Gladiator Resolve -> Saxum Carapace, increases Effective HP but you lose Total HP and crit chance on combo multiplier.
- One of the Carapace Mods -> [Vigor], reduces Effective HP but you gain Total HP.
To run [Primed Vigor] instead, at reduced Effective HP but increased Total HP, lower [Adaptation] to Rank 10 and [Umbral Intensify] to Rank 0.
Umbral Forma
As an extra note, if you use an Umbral Forma on [Umbral Intensify] then that mod can be maxed out.
Helminth
For the Helminth swap, I doubt anyone would argue swapping the Sandstorm out. As for what to, there are options.
For Damage
- Marked For Death - Helminth Rank 6, a powerful ability to be sure, especially on [Inaros] who could potentially combine his blind on Desiccation to allow a Finisher to deal 50% of that damage in a 10m radius around the victim. Other Warframes who can do similar have been shown to insta-kill rooms of enemies, so the power of this option shouldn't be ignored. Testing required due to the low range, but for 50 energy this is a strong option.
- Roar - Rhino - 75 energy for a 30% base increase to damage from all sources for 30s could be nice, but Marked For Death may lead to better killing results.
For Survivability
- Blood Alter - [Garuda], Blood for the Blood God, Skulls for the Skull Throne, and an "Oh Shit" button if you want to regain some HP quickly. 50 energy buys you a 25% missing HP/s, which is very strong when your HP pool is over 9000!
- Defy - [Wukong], Gain up to an extra 750 armour whilst being damage immune for even more survivability with an AoE on self? For 50 energy, why not?
For Utility
- Fire Blast - [Ember], 75% armour strip is nice, and you could swap out Negation Swarm for [Healing Flame] for a weak but welcome heal (25HP per enemy, scales with Strength). Downside is it costs 75 energy, so weigh this wisely.
- Larva - Nidus, 25 energy to group any enemy in an 8m radius into a close area for 7s, making it a useful tool.
- Radial Blind - [Excalibur], a 15s blind in a 25m radius around you feels like an upgrade to your Dessication at twice the energy cost (50). This could yield greater healing potential if the lifesteal is more a passive effect of Dessication than tied to its specific blind, as the wiki suggests. Testing needed.