[Verdilac]'s special Tactical Combo (block + melee) shoots innate toxin projectiles which currently have an unusual damage calculation where [Condition Overload] is multiplicative with other +dmg sources ([Primed Pressure Point], Nira's mods, arcane [Fury]). In addition the projectile damage scales off your combo counter but does not consume combo to use.

Why Gas?
Adding a heat mod combines with the innate toxin on projectiles (not displayed on UI) to produce Gas. While Gas scales relatively poorly against armor and is not scaled by elemental mods, it can be magnified to significant amounts by the combination of [Verdilac]'s weird damage interaction, priming with a secondary primer and achieving max x12 combo. quite effective against groups of enemies and allows the projectile to nuke groups of enemies in a small radius. These Gas clouds also linger even after the initial enemies die so new enemies that enter the cloud are also killed.

Mod Breakdown:

• Condition Overload - compulsory mod since it is multiplicative to +dmg for the projectile, and increases with more status effects e.g. +600% damage at 5 statuses (which can be achieved with Verdilac alone) or +1200% at 10 statuses (which can be achieved with combining a primer and Verdilac's innate statuses).

• Organ Shatter - compulsory mod for crit damage

• Weeping Wounds - useful to increase status chance to 126% at max combo, which makes getting gas procs much more consistent (i.e. guaranteed proc on each hit, with a 26% chance for a second proc).

• Blood Rush - compulsory for crit chance (162% at max combo)

• Primed Fury - attack speed affects regular combo gain and the animation of projectile throwing. Flexible for [Berserker Fury] or drop from build entirely if you run external attack speed (e.g. arcane strike or warframe ability buffs like volt, gauss, warcry).

• Primed Pressure Point - Condition overload is MULTIPLICATIVE with other +dmg sources. If you have any +dmg source from outside e.g. Arcane Fury/blade charger, you can drop this mod entirely for

• Primed Smite Grineer - further multiplier to both [Condition Overload] and +dmg, meaning with +600% from CO (5 status), +190% from Nira and +55% from smite, you get 7x2.9x1.55=31.465x base damage. In addition, smite double dips Gas DoT proc damage to give it a second +55% boost, or 2.401x final multiplier. Swap this for Smite Corrupted/Corpus/Infested depending on faction.

• Volcanic edge - basically required to make Gas on the projectile, a little status helps with making gas procs. You could replace this with [Shocking Touch] to make Corrosive instead for more direct raw damage against ferrite armor, or Primed Fever strike to make pure toxin projectiles against Corpus.

Other flexible options - if you drop Primed Fury or Nira's Contempt due to external sources, or hate faction mods, you can run any of the following alternatives:

• Gladiator might - increases crit chance by 110% at max combo and crit damage by 60%
• Sacrificial Pressure - further boosts crit chance
• Primed Reach - helps build combo but does not increase the radius of projectile or gas clouds

Ability Synergies:
Grouping abilities such as Magus Anomaly, Ensnare, Airburst, Larva or Vortex allow the Gas projectiles to really shine since each Gas proc from an enemy hits all enemies around it, so multiple enemies affected by Gas procs means the group of enemies take an exponential amount of damage. Combining this with AOE Armor Strip is even better e.g. pillage, fireblast, avalanche etc

Sickening Pulse - adds 10 stacks of Gas (to max) and each stack getting the combined damage of all original stacks. This means if you proc 3 gas statuses on the original hit, each doing 1000 damage, the new gas procs do 3000 per tick. If you combine this with grouping, you can speed up the 'nuke' process exponentially.

See Aznvasionplays' video for alternate builds and Gas variant (where I originally got the build): https://www.youtube.com/watch?v=62vdQEqntqo

as well as Dystopia's level cap run video for more detailed proof/calculations on the condition overload interaction: https://www.youtube.com/watch?v=bafjA4HKWMg&t=58s