As with most of my builds, all of them are copies/tweaks of others builds

Binding Gemstones | Steel Path Endurance [Citrine]

Steel Path Endurance focused build relying on crowd control and shield gating. Radial crowd control is essential to prevent damage and the reduce the frequency of shield gating. Crowd control options include Gloom, Shooting Gallery, Resonator, Pull, Airburst, Ensnare or Silence. I have once again chosen Gloom given the synergy of 1 generating health orbs and Equilibrium generating energy and the effect of Gloom prolonging stun from status effects like heat, cold and electric created by 3.

Her 4 also provides crowd control but is expensive to spam, is non-radial (in a cone), has a long cast time that leaves you vulnerable to damage and potentially worsens the damage of your best weapons (it forces 300%CC but requires you to aim at crystals rather than potentially at enemy heads which have a 3x headshot multiplier). You can either subsume Gloom over 2 or 4 depending on preference.

Alternative Casual tank version: https://overframe.gg/build/428715/
SURVIVABILITY (IN ENDURANCE)

Survivability in endurance relies on a combination of juggling crowd control, shield gating and i-frames.

Crowd Control
Crowd control comes from the radial passive slow from Gloom, stun from slash procs on 1 (which are prolonged by Gloom), stagger in 8m on cast of 2, stun from heat/electric procs from 3 (which are prolonged by Gloom) and slow from cold procs from 3 (which can multiply with Gloom) as well as the hard immobilisation from 4 to stop enemies from actually shooting you. Gloom also affects acolytes and demolysts but does NOT work on Eximus with Overguard.

Shield Gating
As soon as you lose shields, you will gain 1.3s of invulnerability. You will simply need to regenerate your maximum shields (75 when Decaying Dragon key is equipped) within this time to refresh the shield gate. You can achieve this by either spamming 1 or by running brief respite + FOUR augment mods spread over your warframe and pistol.

I-frames
Rolling Guard gives 3s of i-frames (invulnerability frames) to give you breathing time to reset shield gate. Finally, Vazarin Protective Dash gives 4s of i-frames with NO cooldown, which is the ultimate backup tool for when Rolling Guard is on cooldown, you are facing eximus units that cannot be crowd controlled or you are out of energy to cast abilities. Vazarin is practically mandatory for a serious endurance run.
BUILD SPECIFICS

Duration
Positive duration helps uptime of 2 and 3 and reduces drain of Gloom.

Efficiency
You can either run neutral efficiency or negative efficiency. Having neutral efficiency is much more comfortable on energy drain and allows you to cast more abilities before running out of energy. Having Blind Rage with negative efficiency allows you to hit the gloom slow cap much easier.

Range
Range is required for the range of Fractured Blast, Prismatic Gem and Gloom. Too much range can be detrimental with Gloom since you slow enemies too far away before you see them, and you end up draining energy unneccesarily. I find 175% range the Perfect Balance.

Strength
Strength is mainly required here for Gloom slow. This also boosts the drop chance of health orbs and energy orbs from 1, significantly boosting energy generation to power Gloom drain. In addition strength increases the status chance/duration buff from 3. Energy Conversion + Molt Augmented + Augur Secrets lets you hit 234% str for 82% slow. If you want to hit the gloom cap of 95% slow (kind of unnecessary in practice), you just need to swap Augur Reach for Umbral Intensify OR run additional external strength buffs like [Nidus] specter, Madurai power sling, zenurik hardened wellspring, pax bolt or power drain.

Aura
Completely flexible.

Enemy Radar - helps with tracking enemy movements so you capitalize on casts of 1 and 4 to catch the most enemies.
Combat Discipline - helps with consistent loss of health so you can take always pick up health orbs to convert into energy through [\[Equilibrium\]](/items/arsenal/831/equilibrium/) (e.g if you dont have Synth Fiber or your pet dies). Having 2 active reduces max rank combat discipline damage to 1.
Brief Respite - allows shield gating without needing augur mods, or allows you to shield gate with 1

Exilus
Handspring interchangeable with Power Drift or Primed Sure footed if you own it.

Flexible Options
Augur Reach - flexible slot if you feel you have enough range for 1,3,4
Natural Talent - This is extremely recommended if you do not use Amber Cast speed shards as both 3 and 4 have ridiculously long cast times. Could slot over Augur Reach or Primed Flow.

Arcanes
Eruption - hilarious map wide knockdown after every cast of 1 since you're bound to generate a few orbs. Gloom extends the duration of knockdown to ridiculous lengths.
Augmented - needed for strength boost for gloom slow. Vigor is an alternative option.
Avenger - can use with Combat Discipline to get flat crit bonus.
ARCHON SHARDS

Armber Shards - 2 to 3 Cast speeds shards is basically mandatory to make Crystallize cast speed bearable, and even then you might want natural talent or madurai power transfer to make it feel better.

Azure Shards - 2 to 3 Energy max shards may allow you to replace Primed Flow as Citrine has a pretty low base energy.

Crimson Shards - nothing specific recommended unless you want to use 2 duration shards.
HELMINTH

I have opted to subsume over 4, but 2 is also an option if you prefer to keep the Crystallize gimmick.

Basically any good crowd control could be used:

Gloom - 95% slow affects all non-overguarded enemies, including Acolytes and Demolysts, but does NOT work on Overguarded
Shooting Gallery with Muzzle Flash augment - this actually blinds EXIMUS units through OVERGUARD, and provides an 8x stealth multiplier to melee attacks, but does not work on Acolytes or Demolysts. If you use Shooting Gallery, you can swap Stretch for Overextended and Augur Secrets for Muzzle Flash.
Resonator - shuts off all aggressive enemy AI, but does not affect acolytes, demolysts or overguard
Silence - shuts off enemy abilities including acolyte abilities (particularly malice and violence) and eximus abilities (particularly annoying Arson fireblasts and Leech zones)
Grouping : Airburst/Pull/Ensnare/Larva

ARSENAL

You could take advantage of the status buffs from 3 and use status based weapons:

Phantasma: https://overframe.gg/build/374667/phantasma-prime/phantastic-phantasma-steel-path-face-melter-with-variant-options/
Phage: https://overframe.gg/build/252696/phage/shocking-tentacles-electic-phage-dot-insane-single-target-dps/
Convectrix: https://overframe.gg/build/413255/convectrix/convectrix-efficient-beams-viral-slash/
Flux Rifle: https://overframe.gg/build/320500/flux-rifle/flux-rifle-slash-overdrive/
Vermisplicer: https://overframe.gg/build/234078/vermisplicer/vermisplicer-primary-viral-slash-anti-grineer/

Kuva Nukor: https://overframe.gg/build/232817/kuva-nukor/kuva-nukor-crit-heat-dps-anti-grineer/