Ultimate [Oberon Prime]
Self revives every 90 seconds. Apart from being a god tank, its just an added bonus.
Efficiency not needed, even if you use this in solo play. Due to [Hunter Adrenaline] + Adapation + higher duration and Optional Arcane Guradians synergy. (as you take damage you gain energy). You'll have more energy then you can spend.
Range - If you really want a tiny, tiny bit more range and are happy to lose +10HP in healing per second (don't recommend). you can increase range by 5m by using [Stretch] - swap to lower rank [Flow] and [Augur Secrets] to [Stretch]. Or a 3m increase by using [Augur Secrets].
Power Strength - you can adjust this as need, but with this build he's already a god. And you don't gain to much more past this power strength without sacrificing another stat. You can build more strength if you run regularly with an EV but you lose the SOLO aspect.
There is multiple builds for [Oberon]. Not limited to removing adaption and [Phoenix Renewal] for other surivial mods like [Gladiator Aegis], Resolve, [Steel Fiber] (his base armor is already so low doesn't really benefit for the cost of the increase) - but note there not as effective at higher levels as this combination.
In regards to arcanes in the patch 27.2 just Arcane [Guardian] is fine. You can use whatever you want in the second slot. Arcane Grace makes [Oberon] even more tanky.
Why adaption Rank 6? - Rank 6 adaption works with multiple Umbra builds. And I highly suggest getting one and keeping it at that level. Gives you a solid % of adapation allowing you to run 2 or 3 umbral mods in many cases with other warframes.
If you like this build please heart it above.