I rather like the idea of the invisible [Gara]: a transparent and deadly crystal.

Archon Shards:

Crimson 10% Str x 2 (important to achieve 200% ability strength for 50% armour strip Pillage)
Amber 50% increased energy from orbs x 1
Amber Casting Speed x 1
Azure 50 increased energy x 1

If you have two Crimson Tau Forged Shards, you can replace Augur Secrets with Umbral Vitality or Umbral Fiber (for more HP on the glass wall)

Introduction:

Nuke/tank/support/heal build. This build revolves around invisibility from Huras Kubrow, armour/shield strip + shield gating + status cleaning of allies from Pillage, combined with the nuke power of [Gara], and healing of allies with Molt Reconstruct. The [Energy Siphon] Aura is also great for supporting teammates.

The aim of this build is to thrive in Steel Path endurance by spamming Pillage and Mass Vitrify to nuke rooms. Due to the spamming nature of the build, Molt Reconstruct will be constantly healing allies, especially non-sentinel companions and objectives such as defense objectives or Kuva Siphons. Even keeping Panzer Vulpaphylas up off of the ground for some amount of time makes a big difference. Armour/shield stripping entire rooms alone will be extremely useful for your allies.

Now with the update, Mass Vitrify will explode both inward and outward. This isn't just a quality of life change for Splinter Storm, but it will also damage enemies inside the wall as well. This means that it will have a potential explosion radius of 40+ metres, AND those inside the wall will take extra damage from the damage susceptibility from vitrification.

The gameplay loop is as follows:

Initial setup:

1.
a) Cast Splinter Storm for damage reduction
b) Build melee combo to 12x
c) Use Mass Vitrify and Shattering Lash to build up Splinter Storm damage to about 1 million (100-200k damage built per cycle depending on your riven)

Once setup, keep repeating 2 :

2.
a) Cast Pillage (2 total casts will be needed for 100% armour strip)
b) Cast Mass Vitrify while Pillage's pulse is going outward
c) recast Pillage (to achieve 100% armour strip) after Mass Vitrify is done casting
d) Shattering Lash the glass wall to nuke mobs (and to build up more Splinter Storm damage)

The aim here is to constantly be nuking mobs while you and your Kubrow remain invisible. In the first few minutes of a Steel Path mission, Pillage won't be necessary as a 12x melee combo and a well built stat stick (see below) will be enough to one-shot Grineer. However Pillage is the main form of shield gating for this build, as the 175% ability efficiency makes traditional shield gating impossible. (Note: this is a calculated tradeoff, and can be swapped for the [Primed Flow] version of the build at the very bottom of the description). Having 1200 shield with 90% damage reduction is a fair health pool, and Mass Vitrify grants invulnerability while waiting for the pulse from Pillage to return to the warframe to restore shields. Pillage also restores shields to your (non-sentinel) companion, effectively shield gating for the both of you. At about level 200 Grineer mobs, a full armour strip will be required to one-shot Heavy Gunners. Also at higher levels, even a 10million DPS Splinter Storm won't one shot Heavy Gunners, and Pillage will be needed. That being said, this build isn't awkward and flows pretty well, and should beat even Saryn in overall damage.

Armour/shield strip in general is key to defeating level 9999 enemies, so getting a full armour strip with Pillage will be needed to have any chance of one-shotting rooms of mobs with [Gara], since the Mass Vitrify explosion will cap out at 'only' 3 million damage or so.

Note that your melee combo will decay over a long period of time. It isn't necessary to keep this maintained to 12x all of the time once you have a million or so damage on your Splinter Storm. The main thing is to remain invisible. You can run [Tandem Bond] on your animal companion to help passively keep up your combo. Also if you kill enough mobs to lose your invisibility, then you can use your melee weapon to block incoming fire to regain combo. You can also use tankier units like Eximus or Thrax to rebuild combo. In these cases, they can survive your Splinter Storm if you don't armour strip them, letting you beat on them for a good while.

The specifics of the build:

-[Huras Kubrow] uses the [Stalk] mod to grant invisibility to itself and you when there is an enemy within 24 metres of you (not 24 metres from the Kubrow). This invisibility lasts indefinitely unless you attack with a weapon, stop moving for 1 minute (anti afk bot system), or there is no enemy within 24 metres for a few seconds. Casting warframe abilities will not break the invisibility, allowing for continuous spamming of skills. https://overframe.gg/build/408947/huras-kubrow/invisible-kubrow-for-gara-ability-spam/ . Ideally you can keep Splinter Storm up on this companion so that it can use [Hunt] to plow through groups of enemies and kill them with Splinter Storm (This won't break the invisibility on the Kubrow). However it is highly problematic to keep Splinter Storm up on a wandering pet.

-Use Mass Vitrify for crowd control as needed, and to kill normal mobs. Use Splinter Storm to kill minibosses like Acolytes or Thrax. You can also bullet jump to kill mobs with Splinter Storm using the 'bowling ball' method (but this is slower than exploding the glass wall).

-Use the Naramon school to maintain melee combo without complete decay (Power Spike), and to build combo up faster (Opening Slam).

-Use the Primary and Secondary Dexterity arcanes to increase combo duration.

-Use a high riven disposition melee weapon (Stat stick). The mods on the melee weapon modify the damage of Shattering Lash (which is incorporated into Mass Vitrify's explosion damage). The key is to have a riven with 430%+ total increased damage. Example here: https://overframe.gg/build/368588/ether-daggers/gara-high-disposition-stat-stick/ .

*With The Duviri Paradox update, I recommend the [Bo] Incarnon. It has high disposition, 7 metres of range(which will hit enemies outside of your Splinter Storm), 70% inherent heavy attack efficiency, allowing for incarnon form to be activated for 100% additive melee damage , and either: 30 increased [Parry] angle with [Umbral Fiber], or alternatively double combo count. If you want a weapon for her glass longword skin, then [Prisma Skana] Incarnon. This weapon has fairly high disposition, but more importantly has 80% heavy attack efficiency built in, allowing for the activation of the Incarnon mode which gives an extra additive 100% melee damage bonus, 6s longer combo duration (as well as 20% movement and parkour speed). It also has a 100% melee weapon damage mod: Bright Purity.

Also note that Ceramic Dagger rivens start at about 500 plat just for something to roll.*

-The second cast of Pillage (100% armour strip) is the largest DPS increase because of the way armour scaling works. It also effectively increases the DPS of all allies as it strips armour/shields on enemies up to ~70 metres away.

-Pillage will cleanse allies of status effects up to a ~70 metre radius. Also you will be healing allies within affinity range for 6hp per energy spent casting (108 from Mass Vitrify alone), granting everyone passive energy regen with Energy Siphon, and boosting their energy with Arcane Energize.

-Have a Miter with the Neutralizing Justice mod, or a high rate of fire weapon to deal with nullifier bubbles

-To keep energy up, the build uses an Amber shard, 175% ability efficiency, [Energy Siphon] aura, and Arcane Energize. I have never had anywhere close to an energy management issue, so some of these aspects could be tweaked.

-Mass Vitrify and Splinter Storm can be used to inflict enemies with damage susceptibility (which stacks from both abilities).

-Splinter Storm can be cast on any ally for 90% damage reduction. Hard to keep up, but with a high efficiency build it is easy to cast on everyone if you have a few spare seconds. If you group up, you only need to cast it once per ally, and your Mass Vitrify spam will automatically refresh it on anyone it touches.

-Energy Siphon is very useful for 175% efficiency builds.

Some notes about the build:

-This build is essentially useless against Archons due to their damage attenuation and immunity to having their armour stripped. (It is fantastic for Archon defense, and keeping the operative alive though!)

-Mass Vitrify sometimes does not refresh the duration of Splinter Storm so try to cast it 2 or more times in the span of Splinter Storm's duration

-Duration seems good with Splinter Storm at 29 seconds. Duration also increases Pillage's maximum range, but it does not speed up the pulse from Pillage, so Pillage will be canceled to speed up the cycle of shattering the glass wall anyway. Therefore, in this build the range of Pillage is already as large or Mass Vitrify's radius + explosion radius which is good enough.

-Range greatly increases the amount of a room that can be cleared with Mass Vitrify, and gives a small boost to Pillage. It also makes an easily managed Splinter Storm which is wide enough to clear a hallway without needing to zig-zag.

-Taking Terrify instead of Pillage gives 100% armour strip in a single cast, but does not strip shields, and does not shield gate for you.

-A [Primed Flow] version of this build can be used. Replace [Fleeting Expertise] for [Archon Flow] or [Primed Flow]. Also replace the 'casting speed' and '50 increased energy pool' Shards for Amber 'increased energy from energy orbs' shards. Replace [Energy Siphon] for [Brief Respite]. Even though [Flow] gives an increased energy pool, you will have less total cast cycles (Pillage > Vitrify > Pillage > Lash) per pool. This is a trade off for the ability to shield gate conventionally, and to have more healing for allies. It will also have a longer duration on Splinter Storm which may help in trying to keep it up on your Kubrow, and give Pillage a larger area covered.

I have an alternate build which maximizes the nuke range to 60 meters found here: https://overframe.gg/build/546849/gara-prime/steel-path-60-metre-nuke-armour-strip-mass-vitrify-one-shot/