Welcome to my Trinity guide.
This guide is the result of many tries, theory-craft and endless runs in steel path survival. It's EASY TO BUILD, doesnt have any MUST-HAVE arcanes and requires no helminth abilities to work.

Nothing's mandatory as long as u use EV-Link or Bless when shields are down, or operator vazarin dash or [Rolling Guard]. U got 5 ways to cheat death.
Rakta dagger makes you kinda unkillable as long as you keep hitting something but all melees are viable, you just have to be more aware of your energy and Link-Bless durations.

You equip a Decaying Dragon key so you can spam overshields, which benefit from adaptation-link-blessing.

My focus school of choice is Vazarin for the protective dash for when u need to shield gate and your [Rolling Guard] is on cooldown or you happen to run out of energy which is borderline impossible to do.

I've played up to 4h of steel path SOLO survival on taveuni with no issue, dying suprisingly only when im caught with Link off and cc'ed or something like that.
[Primed Sure Footed] is a good quality of life. If you dont have it you may also use [Handspring] because getting pulled randomly and staying on your ass while you die or attempting to shieldgate is frustrating.

Usually you'll only need link to be active and melee people to death with the full armor strip with no problems.
Blessing isnt even needed most of the time and when its needed its probably for teammates and not even for your survival.

Warframe Arcanes are up to your choice but guardian/aegis are bad due to low shield and health values. I'd personally advice something to boost your dps such as Melee/Secondary/Primary buffing arcanes.

With [Brief Respite] you can completely shield gate by pressing EV, Link OR Bless, whichever you like. If you lack the energy when the shield gate pops, either vazarin dash or roll for [Rolling Guard] while you get away. Either way you shouldnt die unless you play it very badly or by forgetting to press buttons due to the game being too easy as [Trinity].

Nothing is a threat to you besides Nulliers which you can slap an arcane for easily or shooting them , and the stalkers cousin which deactivates abilities but even then, by using a protective dash-[Rolling Guard] combo you can kill him without him even getting a chance to hit your shields or hp.

My personal primary of choice is [Ignis Wraith] with Primary Dexterity , priming them and shredding with rakta for overshields unless i wanna clean out a room and cc in which case i stick to the [Ignis] for a bit more time. Bonus points if you got [Epitaph], that thing is crazy.

The secondary is unneeded when you get permanent armor strip from Link which offers 100% armor strip at 223 str.
You can run [Zarr], [Epitaph] or generally any secondary as a burst weap or primer. Secondary dexterity so you can keep your Rakta combo up.

Check my [Rakta Dark Dagger] build if you liked this guide <3