TL;DR

This build will one shot most Steel Path content. Anything less and this is gross overkill. Anything that doesn't die from the initial shot will die from the resulting slash procs. I've seen upwards of 150K damage per slash tick. A level 1000 Steel Path Heavy Gunner has 250k HP, so you only need two ticks of slash damage to kill them.

Keep in mind that this build is not about getting the biggest damage numbers out there. There are other [Nataruk] builds for that. This build is instead about maximizing lethal damage to all enemy types with minimal investment. I exclusively use this build with [Zephyr] (mentioned later) in stationary Steel Path missions, and I have yet to feel challenged in a game.

This build works against all classes of enemies because you're bypassing all resists with slash's true damage. Slash damage procs do not scale with elemental damage, so this build focuses on increasing base damage, critical damage, and critical chance. This is why Zehpyr is the perfect complimentary warframe; hovering midair grants an additional 100% crit chance.

You don't need to special case a build for the Corpus because they just die to the insane crit damage. For nullifier eximus, shoot the floating drones on top of their shields to instantly pop the shield.

Here's a brief video demonstrating the build against Steel Path Corpus.

Steel Path Damage

The sort of damage you can expect in the Steel Path:

• Fire a perfect shot, and you'll do around 8k damage on an orange crit against Grineer. With multishot, you'll see three or four of these markers.
• If slash procs are applied, on the next tick you'll see between 20,000 and 50,000 true damage, depending on how many slash procs you got.
• At this point most enemies are dead.
• If the enemy is somehow not dead, shoot again. You'll likely add more slash procs and the next tick will do upwards of 150,000 true damage. Highest I've seen was on a SP Heavy Gunner with 176,000 true damage.
• The only enemies that aren't dead are Deimos Juguli or a Nox. However, they will eventually die to the slash procs.

Why are you not using Viral?

• Stacking viral with a slow bow sucks.
• 10x viral stacks don't make enough of a damage difference to warrant the effort.
• Swapping between primary/secondary just to kill one room sucks.
• Depending on companions to add viral stacks is lame.
• The tradeoff of using additive base damage mods versus multiplicative viral mods isn't justified for the effort required to stack viral.
• This is all explained if you keep reading.

Mod choice explanation

• [Galvanized Chamber], [Serration], [Heavy Caliber], [Vital Sense]: we're trying to get the base damage as high as possible to boost the resulting crits, which in turn boost our slash procs.
  • Slash damage only scales based on base damage, which is why we skip elemental damage.
  • The [Nataruk] has a base slash proc chance of 36% (if status is procced). Adding elemental damage skews the proc chance in favor of other elements, which makes it harder to get slash procs without [Hunter Munitions]. Using a mod to boost slash damage improves these odds, but you lose out on better damage opportunities.
  • The accuracy penalty from [Heavy Caliber] doesn't make any difference.
  • I've tried using [Galvanized Aptitude], but I didn't notice any significant difference in damage output. [Galvanized Aptitude]'s bonus status chance is nice, but the status chance is already really high on perfect shots. Additionally, the bonus damage scales based on number of unique status procs on a target (we can only get up to two with the [Nataruk] alone) and with this build enemies don't live long enough for the bonus to stack. Enemies will die on the second shot without this mod, essentially making the bonus damage useless.
    • If you do choose to use a primer, then yes, [Galvanized Aptitude] will increase your overall damage greatly. However, I don't feel that priming is necessary, as the true damage you can put out with slash procs already slays any enemy in the game.
• [Hunter Munitions]: the core of the build. This is a must.
• [Vigilante Armaments]: flex slot, recommend sticking to multishot. If you've got a riven, this is where you put it. I would prioritize crit damage and multishot.
  • [Bladed Rounds] is an option, but the damage is inconsistent. You only get the buff for 9 seconds. You can get higher slash procs but it's easier to stack more procs than to get fatter procs.
  • A Primed Bane also works here but would require one additional forma. The damage output is already so high that I don't believe a bane would make a significant difference, unless you're fighting level cap enemies.
• [Critical Delay] and [Shred]: this seems like a weird combo for a weapon with already high crit chance and infinite body punch through but hear me out.
  • [Critical Delay] boosts us to get much closer to getting consistent orange crits. More orange crits = fatter slash procs.
  • [Shred] compensates for the fire rate loss from [Critical Delay], but not too much. Too much fire rate makes it too hard to hit perfect shots. [Shred] just barely exceeds the base fire rate enough to make perfect shots still easy, but more frequent.
    • You could take [Primed Shred] but you don't need the extra fire rate. Personal preference. My build is not gospel.
    • The [Nataruk] only has infinite body penetration. This means that if the projectile hits terrain, it stops. [Shred] or [Primed Shred] help by allowing shots to pass through some terrain, which in turn maximizes enemies hit per shot fired. This is particularly helpful with shooting through thin walls or corners of maps.

Exilus slot doesn't matter. Forma the weapon more if you want. [Vigilante Supplies] helps you raise the crit level but the damage you're doing is just so high that it's just overkill.

The projectile size makes headshots easier but aiming is annoying. Take Primary Merciless for the amped damage. Primary Deadhead is inconsistent and Primary Merciless is easier to stack. Additionally, since I use [Zephyr], one shot in a tornado instantly stacks Primary Merciless.

Recommended Warframes

I recommend pairing this build with warframes that group enemies together for you. In particular, I recommend this Zephyr build. [Zephyr]'s passive adds to your crit chance even more and you can snooze through most content in the game.

With this build, you do this:

• Press 3.
• Press 2 in an open area.
• Press 4 to put tornadoes in the middle.
• Wait for enemies to gather.
• Shoot one perfect shot at a tornado. Most enemies die here.
• Wait for one second. The slash procs kick in and everything else dies.
• Repeat forever.

Math

We have a few formulas:

base damage = weapon base damage * (sum of base damage mods)
crit multiplier = 1 + (crit tier, where yellow = 1, orange = 2, red = 3) * (modded crit damage - 1)
slash proc damage = 0.35 * base damage * crit multiplier

Thanks to Serration and Heavy Caliber:

base damage = 900 * (1.65 + 1.65) = 2,970

With this build you will get orange crits 80% the time, so let's do math for that.

crit multiplier = 1 + 2 * (4.8 - 1) = 8.6

for orange crits. With [Zephyr]'s passive, this goes up to 12.4.

A slash proc does 35% of the base damage of a projectile before it is reduced by armor. This is why you'll see this weapon hit for 8,000 damage and then see slash procs seven times larger.

To do the slash proc calc:

slash proc damage = 0.35 * base damage * crit multiplier = 0.35 * 2,970 * 8.6 = 8,939.7

For Zephyr:

slash proc damage = 0.35 * base damage * crit multiplier = 0.35 * 2,970 * 12.4 = 12,889.8

Keep in mind this is per projectile. This means that if you stack [Galvanized Chamber] and [Vigilante Armaments], you'll have 3.9 multishot, which is effectively 4.

That's a 35,758 true damage slash proc on one draw of the [Nataruk], which will kill most enemies in one tick. If you're using [Zephyr], that's 51,559 true damage!