As with any high damage weapon, I recommend Rad + Cold so you get bonuses against Corpus (+shields and +robotic) and Grineer (+alloy armor). The overwhelming rad damage will still take care of ferrite armored enemies except for the heavy ones like heavy gunner and hyekka masters, at which point if you're fighting high enough levels of them, switch to a corrosive or viral secondary like the [Kuva Nukor] or [Pyrana Prime].

The main feature I go for here is DPS. This build features 2 shots (instead of 1) per mag and increased reload speed. This is better for general use as waiting 1.6 seconds between shots/kills to reload sucks for regular use and against most content the 100k damage you can get per shot with pure damage isn't necessary. Much better to pop off two kills with a shorter reload, OR, two shots on one enemy for larger burst DPS.

Only requires 3 forma. Very cheap for a weapon that only has a single polarity, with that polarity being the yucky vazarin. If you want an exlius suggestion, use Fatal Acceleration (increases projectile speed) which increases the effective range of this shotgun to 42-84. Basically a rifle at that point, and without the use of [Vicious Spread] like other builds you will actually manage to hit something at that range.

To summarize this build's key points:
1) Rad + Cold for corpus and grineer
2) 2 shots in a [Mag] for general use
3) Faster reload for general use
4) Low forma cost