This is my current build for running Orphix Venom with friends.
I stopped at 5 forma for now, as this works just fine for the event.

I opted to ignore the melee and focus on having enough utility and survivability to get around the tiles comfortably and stay alive through to 36 Orphix kills (without ever needing to resummon my mech).

I didn't have [Rage] until recently, and energy used to be an issue past Orphix kill 24, as enemy spawns start to drop off and energy orbs become more scarce. Ideally, pair with a warframe that can increase energy orb drop rates, as this is your only source of energy [Regen] for Nechromechs. [Nezha], [Lavos], [Khora] (you can strangldome doorways leading to the Orphix), Protea (or use Helminth to add Dispensary to any other frame if you have subsumed Protea), Nekros, etc.

• Meathook
  This has a heal component. hen you lose health, skewer the biggest meal you can find (Sentients seem to give very little health/s, so grab something else). You can also use meathook to grab a spinning Battalyst and stop their attack, this can save your mech (or your friends) late into a run.

• Shield Maiden
  Directional shield. Grants a short invulnerability buff, during which time, damage taken will be proportionally added to the total shield health at the end of the invulnerability phase.

• Firing Line
  Crowd control, more range does make it better but it lacks vertical heigh either way (despite the graphic). Great to buy some time if you've got the energy to spare, but otherwise you're better off just ground slamming or using your operator's melee/void dash to drag doll enemies without having to pay the energy cost.

• Exalted [Ironbride]
  The heavy attack throws out a projectile, aiming the thing in any axis other than straight horizontal can be an issue though, as the mech takes a huge wind up moving forward in the process. It does good damage but the explosion radius is small compared to the graphic. The general melee from the Ironbrade IMO is terrible; even with all mods, it's still slow, has issues where it physically passes through enemies doing no damage to them. It needs more combos and better [Flow] to be worth building around. It can be fun but doesn't feel rewarding.

Mod choices:
I opted for Thrusters, rather than efficiency as you're generally just moving between the three Orphix spawn points, which gives you time to get max engine again. Slipstream is great for getting there faster; beware of corners.
I didn't feel other engine mods were needed.
Hydraulics; Jump heigh felt like a must, you save a lot of time on certain tiles. Arguably you can use your operator and resummon.
[Rage] if you have it is great due to the Bonewidow's ability to regenerate health with meathook.
Augur and Rebuke add a little survivability/CC and seem more worthwhile than investing in shield recharge/capacity.
[Vitality], [Steel Fiber] and Repair felt mandatory for staying alive long term.
I like having some radar ([Enemy Sense]) and no other mod felt like it was adding anything important. An extra forma to max the mod felt like a waste.

Jump note Double tapping sprint to enter slide then jumping and releasing sprint can save you a lot of engine use as it launches you very far with enough jump height. This is well worth the time to practice doing, you can clear large sections of Jupiter gas city tiles with minimal run-up. Right-clicking to hover acts like an air break.