Hello fellow tenno, and welcome to the amazing world of triple buff saryn, one of the single most broken builds in the game for endgame steel path/arbitrations.

While this build does unholy damage the one tradeoff of this build is just that, it is nothing but insane stat buffs that make any weapon one tap hordes of enemies, oh that and it is bloody expensive to make.

To start with this build the first thing you'll need to get its namesake, is helminth the ability rhinos roar for miasma as you will have 0 range to use it. Roar is the single strongest damage buff ability in the game as it is universal faction damage. You will also need the [Venom Dose] augment mod to gain a 100% ratio corrosive damage buff, which allows you run both corrosive, and viral on your weapon along side with toxic lash to also gain base toxin damage to bypass sheilds making this build nuke every faction in the game.
For that same reason that you have corrosive and toxin at such a high scaling, it makes fighting the profit taker laughably easy as over your 3 weapons you can run 11/12 elements to damage the sheild, that combined with roar makes each run insanely fast.

While the [Umbral Vitality] and [Umbral Fiber] mods are not completely necessary due to the fact that you can abuse operator invulnerabilty, and heal your frame with multiple operator arcanes, they are however, incredibly useful with the link health and armor mods for making sure your smeeta/pet are nigh unkillable which, in arbitrations very much helps if you're doing endurance runs, especially against infested.
If you cannot run those mods you can alternatively run regular vitality, fiber, and intensify/[Transient Fortitude].

[Narrow Minded] and [Primed Continuity] make it so that with the negative energy efficiency of [Blind Rage], you don't need to energy pizza or run energize before you need to reset the next round of buffs.

For the aura mod that comes down to personal preference, me personally I prefer [Enemy Radar] as along side with [Primed Animal Instinct], I know exactly where the next round of enemies spawn the second the previous die which helps with clear time.

[Adaptation] broken lul.

[Primed Sure Footed] broken lul.

For arcanes you can run [Guardian] for more survivability for yourself and your pet, and I like to run molt augmented as with it, it makes some weapons like the [Ogris] just one tap before the aoe effect of napalm, while also giving enough damage to make sure eximus still remain only needing 1 shot to deal with instead of 2.
Other alternatives for molt would be energize or another defensive arcane.

For weapon choices, to get the most out of this build I strongly advise running an aoe weapon, of which I highly reccomend both the [Kuva Ogris] for its ability to kill enemies in their spawn twice over in 1 shot with [Nightwatch Napalm], or the [Kuva Bramma] for its use of [Hunter Munitions] which applies all of those buffs to its slash proc damage. If you cannot run these weapons, some good alternatives are the [Kuva Zarr], [Lenz], or the [Ignis Wraith].

Now if you're facing a boss type enemy I'd reccomend the [Nataruk] for its exceptional base damage and crit stats, and the fact that its free. Another phenomenal choice is the [Kuva Hek] as it has very high base stats being a kuva weapon, but also has an alt fire effect where it fires all 4 shots at once, allowing you to blast through boss attenuation with its insane multishot count, very effective vs archon bosses right now.

As I can attest from running 100 waves+ in defense arbitrations if you run a decent aoe weapon with this build you will still one shot enemies level 2000-3000+, while still being near unkillable, and in interception with an [Ogris] or bramma you will easily clear the map in seconds for that sweet, succulent vitus.

Thank you my fellow [Saryn] abusers for taking the time to read my guide I hope this build helps you in clearing steel path, or doing better in arbitration clearing, and so my friends have a nice day ;)