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 Veteran Build - Warhammer 40k: Darktide 

Whole point of this build is to have as much grenade damage as possible, but if you can't withstand some situations, I rather recommend swapping Focused Fire to Overwatch to boost survivability.

Infiltrate suppresses all ranged and applies minor stagger to insuppressible enemies (all melee, even Dreg Shotgunner, Scab Shotgunner and Scab Plasma Gunner, they're coded as melee enemies). This will trigger Opportunist and Execution.

Orestes Mk XII Assault Chainaxe push attack can stagger Crusher. Rev-up attacks apply stagger state to all enemies except Mutant and all boss enemies (Captains, Monstrosities, etc.)

If you don't like Serrated Blade and find yourself throwing grenades more than fighting in melee or you're feeling aight without it, change it to Field Improvisation, which additionally in some occasions will increase survivability even more.

Just to further clarify if anyone questions Opportunist:
It is stated that Headtaker gives strength on kill, but in code it's actually melee power and not global strength, when Slaughterer having almost identical description actually gives global strength. So 2nd blessing that boosts our grenades the most is Opportunist.