For this method to work you need to suplement it with either this Fluctus build or this Mausolon build

Difference between 2 weapons is

Fluctus - CANT destroy Orphix with it (well it can but its very hard to find perfect spot) can shoot trough walls/objects easier to destroy Orphix Resonator but requires clicking fire button rapidly

Mausolon - CAN destroy Orphix and have more DPS but requires line of sight with Orphix Resonator to destroy it while its autofire (hold fire button to shot)

And here is the trick personally i go with Fluctus cause i destroy more resonators and enemies trough walls/objects than "Orphix'es"

For Orphix himself i just use Guard Mode (press 4) and destroy him with Arquebex

TIPS
HEALING -> [Vizier Predasite] with mod [Iatric Mycelium] (you get it with that Predasite) leaves trail if you step into it ur Necramech will be healed
After few runs with mod setup from above turns out u become kinda immortal as long as u keep ur Storm Shroud ACTIVE (making [Combat Discipline] useless and allows u to sustain urself no matter who u got in ur squad and what they do)
[Combat Discipline] Aura works on Necramech except ur own so when you kill WHILE IN Warfram all squad members Necramech (or in whatever they are in at the time) are healed except your own Necramech
You cant avoid that animation after you stop sliding but you can [Negate] it by jumping at the end while still sliding
Activating Storm Shroud (press 2) while getting attacked from many sources is good idea since you get 3 seconds invulnerability time frame in which all incoming damage is multipied into Storm Shroud's HP
IF you are taking beast companion (for example Smeta Kavat) with you i suggest going with Inaros (throw into him all HP/Armor mods u can find) + Link Armor + Link Health on your pet since that kinda wont let him die
Orphix Spawn rotation is (START A B CC) then A BB A CC repeat in other words if spawn location occurs and it DOES NOT repeat but just switches to next one then this is spawn A
If you look at map B will be close to A while C will be the farthest spawn from the two
And just follow this pattern START A B CC) then A BB A CC A BB A CC.....and so go on
How it works
Shoot trough walls/objects all Orphix Resonators (best idea is to aim little below red waypoint)
Go to Orphix and stand in front of him just so his eye is visible
Go into Guard Mode (press 4)
Fire until it die
In meantime activate Storm Shroud (press 2) to [Protect] Necramech from damage (just keep it active)
Repeat
Enjoy
I just want to point out that at Orphix Venom Endurance killing 36 while using builds included here + method from above WITHOUT paying big attention to Storm Shroud but just checking it from time to time i die like 3 tiems around 25+ Orphix if i pay attention to Storm Shroud i dont die at all

And so far with random squads i am main damage dealer
When my Necramech dies they struggle to do constant damage seems no 1 is prepared for this battle and 99% of them try to kill it with archgun instead of [Arquebex]

This build is interchangeable with my [Voidrig] Necramech 3D build