This is a Steel Path and Veil Proxima Grineer faction build. It strips their armor completely and plows through their health in about 2 seconds. The eternal argument of viral versus corrosive damage comes into play here. In my testing and research, the answer to which one works better really comes down the weapon, the way you build it, and the amount of armor the target has. Having [Vile Acceleration] or [Speed Trigger] with the [Ignis] allows corrosive and viral to both work well, however, the difference between them is based on the level of the enemy. For levels up to 60 and maybe even 1st stage sorties, viral damage type works better. For anything level 100 and above, corrosive works better. The reason being is how long it takes to kill enemies using viral proc bonuses when the armor is insanely high. For high armored enemies level 100 and above, viral takes longer and has lower KPS. At those levels though, corrosive procs strip armor completely with the high status and fire rate of the build and then goes to town on the remaining health of the target much more quickly, thus yielding a higher KPS. So use this same build with viral damage on level 80 and lower, and for levels higher than that use corrosive damage. There is no better weapon in the game for taking out highest level Grineer.