What memories when [Tonkor] allowed you to shoot a meter away and destroyed the shield and the health of your Warframe... Not being blown up... those things we can never [Recover], but what if we can [Recover] it's your two grenade magazine! And that's what this little build is based on, but let's review it point by point.

The magazine:

[Tonkor] has a very fast firing rate but only 1 magazine capacity, if you [Reach] +50% Magazine Capacity the game rounds up to 2 magacine capacity!
We achieve this thanks to [Primed Magazine Warp], Does not have [Primed Magazine Warp]? Use [Tainted Mag] instead at rank 8!, this mod has a reload speed penalty and we want it to be as low as possible but obtaining at least the 50% extra magazine capacity.

Damage types:

You can use practically any damage combo on this weapon.
Personally I like to use the Viral + Slash combo.
Viral can be achieved with [Primed Cryo Rounds] and Toxin as Kuva element.
The slash comes from [Hunter Munitions] (what a surprise) which takes great advantage of the weapon's high critical probability.
The weapon does not have a very high status probability, because as a general rule it kills with a single hit. I think it is best to ignore this attribute.

Critical hits:

This weapon have a very high base critical probability, easily reaching 90% if you use [Critical Delay], No [Critical Delay]? Use [Point Strike] instead and [Reach] 75%.

Exilus:

Thanks to the fact that DE changed [Cautious Shot] from 90% to 100%, it is now really worth using it, believe me. It does not make you immune but it saves you a lot of time on the ground.
You do not like? I recommend [Terminal Velocity] instead, you will be able to [Reach] great distances both indoors and outdoors.

Damage vs Area:

With this build the weapon deals 880k burst damage in a radius of 7 meters. With this damage you will kill level 180 Corrupt Heavy Gunners with a single shot!
Although if you think about it, this situation does not happen very often, right? Personally, I like to substitute Serrationfor [Primed Firestorm], going from 7 meters to more than 11.5 meters, which implies an area 3 times larger, this maximizes the damage to multiple targets!
This way is even more recommendable to use [Cautious Shot], I also recommend removing [Serration] and not [Heavy Caliber] since reducing the precision of the weapon will cause the grenades to fall slightly apart which will increase the explosion radius a little more.

And that's all! Happy Hunting!