Welcome to the Fortuna Space Program's Brash Knuckle. Looking for a primary boomstick to launch your friendly neighborhood Grineer into space? Look no further.

This is a Primary [Tombfinger] build, but due to limitations on overframe.gg, it gets piled up with the secondary. It's also unfortunately a rather Forma-heavy weapon, like most kitguns.

Let's start with the components of the kitgun first.

1. [Tombfinger]: This is what you're here for. Maybe you got a [Tombfinger] riven that absolutely slaps. Maybe you want a boomstick that has a ridiculous amount of ragdolling. Maybe you saw the Tier List section and noticed the [Tombfinger] is the 5th most popular secondary and you clicked on it, and saw this build. Either way, you can't go wrong with a [Tombfinger].

2. Brash: Basically, among the Primary kitgun grips, there are two most popular options: Brash, a high fire rate/charge rate grip with reduced damage, and Tremor, a grip with high damage with, you guessed it, reduced fire rate/charge rate. You can pick either one, these are mostly chosen by personal preference. You want to one bang the Grineer even harder? Tremor is perfectly fine. But personally, since kitguns in general have an astronomical amount of ammo (over a thousand, and literally infinite if you use Pax Charge) and really good loader option for reload rate/charge rate, I opted for Brash to let me rain down explosions even faster. Tremor WILL give you around 35% more damage on your average hit, in exchange for significantly longer charge rate. This is a classic Opticor vs Opticor Vandal situation here, so pick your poison.

3. Killstream: Fast recharge/reload rate means more booming, less fiddling. Maximum critical rate is essential as you need it to break through the 100% critical rate barrier with [Critical Delay] or approach it as close as possible with [Point Strike]. This is a [Hunter Munitions] build and thus we make no compromise on the critical rate. The more critical chance, the higher we can proc the delicious slash procs.

With that out of the way, let's jump straight into the build.

1. [Terminal Velocity]: Needless to say, this gun is a boomstick with a traveling projectiles. Although these projectiles have a very short travel time already, [Terminal Velocity] helps a little bit more in the case that you want to bring your rocket launcher to launch the Grineer 300 meters away from you in the Plains of Eidolon into actual space for example, or maybe you noticed the thing fires radiation damage projectile and you want to give the eidolons exploding knees. Either way, if you want to save 20 plats, you can ignore the Exilus slot as this slot is not a necessity at all, merely a convenience. You don't ever even need Max Ammo or Ammo Mutation on this gun: at the point of this writing, I am looking at my Brash Knuckle with over 1000 bullets in reserve.

2. [Hunter Munitions], [Primed Cryo Rounds] and [Malignant Force]: The bread and butter of 2021 Warframe. This is what we picked Killstream loader for. This is what strikes fear in Grineer's heart right through their stupid scaling armor. The combination of armor-ignoring slash proc damage from a critical strike thanks to [Hunter Munitions] and the effect of Viral proc amplifying all damage on enemy's health proves fatal to the enemies in the most important scaling content in the game. If you don't have [Primed Cryo Rounds], I recommend going with [Rime Rounds] instead of [Cryo Rounds], as the increase from 30% more cold damage from [Cryo Rounds] is negligible and the extra status chance from [Rime Rounds] is a very welcome addition as we do want as much Viral proc as possible, and we already have a somewhat diluted proc pool with almost 25% radiation damage from the weapon innately.

3. [Critical Delay] and [Vital Sense]: The inevitable conclusion. We need slash and viral proc to kill the toughest enemies. We need critical strike to apply the slash proc through [Hunter Munitions]. Thus, we need critical strike chance and critical damage. As much of them as possible. While [Vital Sense] is the only mod with unconditioned bonus for critical damage and thus the obvious choice for critical damage (there's also [Hammer Shot] but we'll talk about that later), [Critical Delay] and [Point Strike] somewhat serve the same purpose and you can only choose one of them. Statistically, they both have their pros and cons: in a [Vacuum], [Critical Delay] will give us bigger average hit damage and lower burst and sustained DPS, and [Point Strike] is the other way around, as it gives us more burst and sustained DPS but takes away quite a chunk from our average hit damage number. I say "in a [Vacuum]" because usually this kind of difference is only perceptible in a simulacrum, with an immortal enemy that you can continuously plink at for however long duration you want. In actual gameplay, the fire rate penalty from [Critical Delay] has a lot less effect than one might think.

4. [Galvanized Chamber]: There is no endgame build worth a salt that doesn't have this mod on its build. This mod is almost 3 times as effective as a [Split Chamber] at max rank and full charge (230% vs 90%) and pretty much just as good as Split Chamber at max rank without any charge required (80% vs 90%). It's almost a no-brainer, this mod should be slapped on just about anything you can get your hands on and then some.

5. [Vile Acceleration], [Bladed Rounds]: We're now in territory of optional slots. I like [Vile Acceleration] because 0.6 sec charge duration is honestly still not comfortable enough for me (I shudder at the thought of using Tremor grip). If you use Tremor grip however, Vile Acceleration is non-negotiable: the 1.7 second charge duration WILL make you [Hate] yourself and question the sanity of those Fortuna dwellers, whether the coolant in the water turned their brain to mush or something else made this monstrosity possible. As for [Bladed Rounds], I simply selected it for 3 reasons: I [Hate] swapping bane mods back and forth for racial bonus, I don't think I need more area of effect as ~7 meters explosion range is quite plenty, and [Bladed Rounds] give me a really decent chunk of damage on every enemy type when I got a kill recently (read: all the time).

You actually have quite a few options for these flex slots so let's go through them really quickly.

1. [Vile Acceleration] is as mentioned, a mod that brings your charge time down to a comfortable 0.3 second if you're using Brash grip and is a must have on Tremor grip to bring the charge time down to 0.8 seconds. This is a must on Tremor grip. Important things deserve being mentioned twice. Another bonus point is that you will inevitably run into Corpus Nullifier Crewmen eventually. Instead of having to fumble about with some secondary or having to build some high fire rate amp for your Operator, you can just click their heads a few times before they are... repossessed, one might say, as you do have very healthy fire rate from [Vile Acceleration].

2. [Bladed Rounds] is also my mod of choice, as it gives you a decent chunk of damage to every enemy type as long as you have killed recently. One rather bad place for this mod is a boss fight. Usually there isn't any grunt around for you to kill when you're fighting a big bad, and having to refresh the buff by shooting some grunt every 9 seconds is not exactly what I call fun either.

3. [Hammer Shot] shot up in popularity a while back when DE gave it quite a lot more status chance. The reason I did not consider this an option in replacement for [Vital Sense] is that... it simply isn't. Unlike [Point Strike] and [Critical Delay], where you have to choose one out of the two to slot into your build, you can use [Hammer Shot] alongside [Vital Sense] perfectly fine. This is my primo choice for my lazy days, for when I don't want to replace [Bladed Rounds] back and forth, yet still have a healthy amount of critical damage AND some more status chance for more consistent status proc to boot! And don't get me started on bane mods.

4. [Firestorm] and [Primed Firestorm] are staples of explosive weapons. More booming means you have to shoot less to kill more. My testing has led me to believe that the Brash Knuckle has ~7m explosion radius, which is boosted to ~9m after [Firestorm] and ~12m after [Primed Firestorm]. Not the biggest, but not the worst.

5. Bane mods are options that if you seek, you probably [Hate] the Grineer more than I do. Pros: Primed Bane Mods are the biggest damage boost you can get. Cons: It's racially conditional and you need to swap them out mission to mission.

6. [Serration] is actually a decent option if you, unlike me, can't use an Arcane [Rage] on your Warframe. [Serration] will give you a decent amount of damage to start with, and even with opportunity cost considered with Primary Merciless on the weapon at max stacks already, [Serration] will STILL give you a 37.1% more modifier if you have [Vile Acceleration] in the other optional slot already. [Amalgam Serration] is worth a honorable mention here as I do think it's worth using over the normal version just for the utility of sprint speed.

7. [Heavy Caliber] is another option aimed for newer players who don't have a big arsenal of mods, along with [Point Strike] in place of Critical Delay, which will free up the Vile Acceleration slot as you no longer need to compensate for the reduced fire rate/charge rate and now you can use [Serration] and [Point Strike] instead of [Vile Acceleration] and [Critical Delay], and [Heavy Caliber] in the last slot.

8. [Galvanized Scope] is an option that I also tried around with. It does give you a hell of a lot of critical chance, pushing your gun into pretty much orange crit on every single shot and some red crit. If you keep the buff going and also have Vigilante mod set equipped on your sentinel weapon, you will see so many red crits your eyes will bleed. However, I can't recommend it in good faith because you have to do something that goes against the tenet of explosive weapons: you have to aim for the head AND kill with it. And since we're using a slash proc weapon, there's a non-zero probability that you will sometimes not able to proc the Headshot Kill portion of the mod, as slash procs kills do not count as a headshot kill. Furthermore, the buff on it also drops straight from 5x charge to no charge, and until DE decides to change this behavior, this mod will be a huge pain in the ass to sustain. The only weapon I can imagine [Galvanized Scope] is good on is the [Kuva Bramma], as that's the one explosive weapon you can detonate on air over the enemies and reap those headshot kills repeatedly. If you DO decide to use this mod, however, it should go in and replace Hunter Munition. The headshot damage is ridiculous enough that unless you do endurance run, most things won't stand long enough to take the second shot. It's certainly a viable build for a certain playstyle.

9. Elemental mods such as [Thermite Rounds], [High Voltage] and such also have their place in the build. Obviously, we have [Primed Cryo Rounds] and [Malignant Force] as we need Viral procs to amplify slash damage, but there's also an argument for replacing [Malignant Force] for [High Voltage], as Magnetic proc does the exact same thing as Viral, except it amplifies damage to shield instead of damage to health. A third elemental mod is not a bad idea, but if you do go about it, I recommend going with a 60/60 mod instead of a 90 mod, as we would rather get more status chance to make viral proc more than diluting our elemental pool even further than necessary. You CAN go with a 90 mod if you remove [Hunter Munitions] and instead rely on raw damage to kill everything but I doubt that build will get far.

Now, time to talk about Arcanes. While it's true that Arcanes mostly are there to give you bigger number, some of them also influence how you use a weapon. The arcanes I mention in this section will mostly be options that are most obvious or directly affect the playstyle of the weapon, not every Arcanes that can help you [Reach] ridiculous amount of damage.

1. Arcane [Rage] is my Warframe arcane of choice as just a single shot to the head of an enemy gives you its +180% damage buff. This is considered weapon damage and is the same type as [Serration] and [Heavy Caliber]. With this on, you can easily ramp up the buffs at the start of the mission without having to deal with doing negligible damage for a while before everything starts rolling.

2. Arcane Primary Charger on your Warframe and Primary Dexterity on your kitgun are also a pair of very strong Arcanes if you have a decent way to kill enemies easily with a melee weapon. An initial combo heavy attack melee build with CO plus a primer secondary will allow you to quickly dispatch 6 enemies in no time and net you that +660% damage buff easily peasily. It however goes against the spirit of the weapon so it's up to you to choose whether or not to use it. I don't.

3. Pax Charge and Pax [Seeker] are the two options you can choose for Kitgun Arcanes depending on the way you want to build this weapon. If you strictly just want a boomstick that you can point at a group of enemy and fire, Pax Charge will be the arcane you want mostly, as it removes the need to reload almost completely. However, Pax [Seeker] is a very strong option as well. On a build with [Galvanized Scope] and Primary Deadhead, you will be slamming headshot after headshot after headshot, ramping up the critical damage buff and when you do that, you will be proccing Pax [Seeker] on every headshot kill, sending out projectiles that automatically seek nearby enemies and more often than not, hit them right in the dome. These projectiles become stronger with your damage and if they kill the enemies through a headshot, you will obtain a charge of the Headshot Kill portion of [Galvanized Scope]. This means that Pax [Seeker] doubles as both a crowd control measure and also a tool to help you ramp up the charges really quickly. It has very limited usage in tight spaces though, so bear that one in mind.

4. Primary Merciless, Primary Deadhead and Primary Dexterity are 3 options for 3 completely different playstyle. Primary Merciless is your generic "more damage Arcane, while Primary Deadhead will allow you to amp up your headshot damage even further if you build for headshot, and Primary Dexterity** will be very useful if you like using your melee weapon a lot.