[Oberon] is my favorite Warframe and I by no means am expert on this game.
And lets be Frank he's not the best for Steel Path, but I enjoy the Class fantasy of him.

Ever since Umbra mods came out I've wanted to make a full umbra build for him.
By no means is this a perfect build but its my build that I've enjoyed playing and having fun in the steel path.

So at the start this of a mission needs to build up Molt augmented to get full power str.
But even with not having 200 power strength it only takes two cast of hallow reckoning to rip armor.
Once you max it out with this build then its just one cast.

You also only heal for 47 sec and give 230 armor at first.
As you get more kills to get Molt Augment up then you can get much higher at 81hp/s and 404 armor.
Which isn't a lot but combining Arcane [Guardian] umber fiber and your heal. you should have almost 84% damage reduction.
And with [Adaptation] that will seriously makes you tanky.

Energy is handled by using nourish with [Hunter Adrenaline] and orbs you shouldn't ever run out of power.
I also like to run with [Sahasa Kubrow] for their [Dig].
This way beginning of mission you almost full of power and threw out the mission they will [Dig] once in a while in a pitch.
Plus I named mine after my real life dog.

We are immune to status procs as long as we are on our grass.
Now while on your grass you shouldn't be able to get knocked off but I've noticed it still happens from time to time.
But once I put on [Primed Sure Footed] this stopped, and with the almost 200 range the grass is everywhere.
I've had alot of people common everything is covered in grass lol.

For Archon shards.
My recommendation is two orange shards with casting speed. So you can rip armor off quicker.
Then rest is up to you. Personally I've done two red shards for more power strength because why not more armor and healing per sec.
And one blue just for extra 150 armor. Because I had extra blue shards. Most likely the best option is to go 3 red.
Play around see what you enjoy. :-)

Thanks for looking at my build and I hope you guys enjoy it.
Its not a cheap build but [Oberon] is my favorite frame.
Hopefully in time DE gives some some number reworks like updating his passive and maybe less energy cost and increase range.
But only time will tell.

01/14/23 replace hunter with hallowed reckoning going to be testing that soon

If you like to see the current pet build i like to run with this.
https://overframe.gg/build/541293/sahasa-kubrow/sahasa-for-oberon-and-silva-aegis/