So you probably came because of wanting to use tonfas but you don't have Kronen Prime. Well, Ohma is not worse than Kronen at all.

CO, BR and WW is the meta - theae three mods are absolutely mandatory.

[Primed Reach] imo is a must if you want maximun enjoyment, Berserker is insane since I use [Valkyr] all the time and you can still use Warcry should you unlock Helminth system and subsumed a [Valkyr]. [Fever Strike] to make corrosive for the damage boost. Feel free to replace it with its prime variant as I simply use [Fever Strike] due to not having the Primed version of the mod.

[Drifting Contact] for status chance and combo duration. You can swap [Drifting Contact] for a riven, or [Primed Pressure Point] of you run Naramon Focus school. Do mind though that if you are using Warcry then stacking combo is easy as pie, so Naramon does not benefit too much if you don't care about having to constantly stacking the combos.

[Healing Return] is a forgotten mod, and it could be busted with this build. You are going to heal for 11 for each status effect, and this build gives you 174% status, which you have 74% to proc a second status on the same target. You are going to hit multiple targets, so you are going to heal for hundreds just by one attack, let alone the combo. Get a high resistance warframe and enjoy immortality.

Stance does not matter, but [Ohma] came with a Naramon polarity on the stance, so [Sovereign Outcast] is the stance I am using.