The Devouring Void | Raw Non-crit Viral Heat Laetum (One-shot Steel Path)

One of the strongest weapons in the game currently. The primary fire feels like a lex prime but hits a truck. Getting 12 headshots charges up it's Incarnon mode (can be shortened to about 3-4 shots with multishot). Switching to Incarnon mode with alt-fire makes it feel like a pocket Acceltra with small AOE on impact but with significant damage. This build is a raw damage non-crit build using Devouring Attrition.

Other build options:
Crit Viral Heat Overwhelming Attrition (higher potential single target DPS): https://overframe.gg/build/315013/
Viral Slash Devouring Attrition (scales better against armor against single targets) : https://overframe.gg/build/316948
Evolution Choices

Evolution I - Incarnon mode

Evolution II - Rapid Wrath: +20% Fire rate. Can use recoil perk if you don’t use one of Secondary Deadhead or Steady hands.

Evolution III - Lethal Rearmament: +90% reload speed on headshot at 3 stacks. This also shortens the transformation animation to Incarnon mode from approx 3s to 1.5s. Currently the Feather of Justice perk is bugged in that it applies to other weapons
too, but I expect this will get patched

Evolution IV - Elemental Excess +20% status, -10% crit chance. Reducing crit chance increases the likelihood of Devouring Attrition boosted shots.

Evolution V - Devouring Attrition: 50% chance to do 2000% damage on non-critical hits. This is currently multiplicative to base damage mods such as [Hornet Strike] and double dips the void damage instance of [Xata]'s Whisper. 

Calulations of Devouring Attrition vs Overwhelming Attrition
Devouring Attrition

With no crit mods + hornet strike (2.2) + deadhead (3.6) + elemental excess (-10% crit):

88% chance to do no crit with 50% chance to get 2000% multiplicative with hornet strike/deadhead
- 44% chance to do 21x(1+3.6+2.2)=142.8x
- 44% chance to do 1+3.6+2.2 = 6.8x
12% chance to crit and do (1+3.6+2.2) x 2.2=14.96x

Average Damage multipliers
44%x142.8 + 44%x6.8 + 12%x14.96=67.6192x on bodyshot
(44%x142.8 + 44%x6.8 + 12%x2x14.96) x 2.3=159.6x on headshot

Void damage instance with Xata's Whisper
On bodyshot: 44%*142.8x21+44%x6.8+12%x14.96=1,324 x base damage x Xata's Whisper % (Xata's whisper double dips Devouring attrition)
On headshots and taking into account faction mods, this becomes 21,502 x base damage x Xata's Whisper% (Xata's Whisper also double dips 2x headshot multiplier, 1.3x bonus of deadhead and 1.55x of primed bane)
Overwhelming Attrition assuming 100% uptime at max stacks giving additive 1200% on all hits:

With [Galvanized Crosshairs] (max stacks), [Primed Target Cracker] and secondary deadhead (max stacks):

92% crit chance to do (1+3.6+12) x 4.62=76.692x
8% chance to not crit 1+3.6+12= 16.6x

On headshots, tier 1 crit multiplier is 2.8(1+1(2*4.64-1))=25.984 (with secondary deadhead 0.3 and caput mortuum 0.5 multipliers additive to 2x headshot multiplier)
Headshot damage is then (1+3.6+12) x 25.984=431.3

With [Primed Pistol Gambit], [Primed Target Cracker] and secondary deadhead:

63% chance to do (1+12+3.6) x 4.62=76.692x
37% chance to not crit and do (1++3.6+12)=16.6x 

Average Damage Multipliers

No headshots and running [\[Primed Pistol Gambit\]](/items/arsenal/415/primed-pistol-gambit/) (63% crit): 63%x76.692+37%x16.6=54.458 =53.126x base damage on bodyshots (lower than devouring attrition by 20%)
No headshots and running exactly 85% crit chance: 85%x76.692+15%x16.6=67.6782x on bodyshots (Just exceeds devouring attrition).
No headshots but running max stack [\[Galvanized Crosshairs\]](/items/arsenal/5516/galvanized-crosshairs/) (92% crit): 92%x76.692+8%x16.6=72x base damage on bodyshots (exceeds devouring attrition by 35%)
All headshots: 92%x431+8%x47=399x base damage on headshots (this is because headshots double dip crit multiplier bonus and Caput Mortum adds onto Deadhead for 2.8x headshot).

TL,DR:

Use Devouring Attrition if you don't want to aim at heads and just spam AOE shots (67.6x multiplier vs 54x multiplier on bodyshots using Primed Pistol Gambit) or want to abuse Xata's Whisper's 441x double dip.

Use Overwhelming Attrition if you want to be more precise and aim at heads for up to 3x higher damage (398x multiplier vs 159x multiplier on headshots and 72x multiplier vs 67.6x multiplier on bodyshots after galvanized crosshairs stacks).

See Overwhelming Attrition build here: https://overframe.gg/build/315013/
Mod Breakdown

[Galvanized Diffusion]: +230% multishot at max stacks, meaning you get at least 3 bullets per shot with a 30% chance for 4. This allows you to basically do 3x more damage AND charge incarnon mode 3x faster.
[Hornet Strike]: +220% damage which is multiplicative with devouring attrition and additive with secondary deadhead but helps initial ramp up before any deadhead stacks are active. [Galvanized Shot] is not used here since it does NOT work on the AOE component (which is responsible for 3x more raw damage compared to direct hit). This is the FLEXIBLE SLOT if you use secondary deadhead.
Primed Expel: A further 1.55 multiplier to hornet strike/deadhead and Devouring Attrition and double dips on heat procs giving them 2.4x multiplier. Use regular expel mod if no primed version as it is still a 1.3 or 1.69x multiplier.
[Lethal Torrent]: Brings multishot to 3.9 so 90% of shots give 4 bullets, and gives fire rate (combined Rapid Wrath gives +80% fire rate total)
[Primed Fulmination]: Brings the 2m AOE component to 3.3m to give it more spread capability. This is flexible for anemic agility or scorch. This is a FLEXIBLE SLOT
Viral 60/60: Gives status chance and viral procs. One viral status gives a 2x multiplier on all subsequent hits, adding up to 4.25x multiplier at max 10 stacks.
[Primed Heated Charge]: Biggest elemental mod bonus on pistols to multiply raw damage. Heat procs also strip armor by 50% and can stack indefinitely, which each new stack refreshing all existing stacks.
Steady Hands: Combines with Deadhead or recoil perk to give -100% recoil for laser point accuracy. [Lethal Momentum] is an alternative but this requires changing polarity.

Flexible Options
These can be added over either Primed fulmination or Hornet strike:

Anemic Agility - can swap over hornet strike or primed fulmination for slight technical sustained DPS boost.
Augur Pact - mostly useful for Augur set bonus for shield gating and minor damage boost
Riven:
Best Positives : multishot, damage, fire rate
Okay positives : status chance, toxin, reload speed
Best Negatives : crit chance, zoom

Arcane

Secondary Deadhead: Long upkeep times of +360% damage and gives -recoil and +headshot multiplier. This is the recommended arcane, but just needs headshots
Secondary Merciless: Doesn't need headshots to upkeep, but stacks fall off quicker, and you get a neat reload bonus that helps with transform speed. Not recommended unless you [\[Hate\]](/items/arsenal/1155/hate/) aiming for heads
Cascadia Empowered: Currently, Devouring Attrition multiplies each 750 damage proc of Empowered by 21 giving 15750 damage per instance (but at 50% rate per status). This is a very nice damage bonus when it procs and is an interesting option unless it gets patched. Consider using the -recoil perk instead of +fire rate if you drop deadhead).

Other Factions

For Corpus: Swap Frostbite and Primed heated charge for Pathogen Rounds to make pure toxin and add anemic agility.
For Thrax/Acolyte (without strip)/Infested: Swap Frostbite for Jolt/Convulsion to make Corrosive Heat
For Angels/Eidolon: Swap Pistol Pestilence and Frostbite for Anemic Agility and Convulsion. Drop expel mod for Jolt.
Xata's Whisper interaction

Devouring Attritions 2000% multiplier double dips on Xata's Whisper void damage instance in that it applies twice to give a final multiplier of 44,100% or 441x.
You can see that here where Laetum can basically one-shot steel path Grineer demolysts with NO armor strip and NO priming:

https://www.youtube.com/watch?v=aFgMUfJUkK8