Chain & Shotgun Zealot
 Zealot Build - Warhammer 40k: Darktide 

Spamming lights with the Eviscerator will clean up hordes pretty tidily and safely, with your crits providing significant cleave/bleed/and defensive perks. Use revved heavies vs Crushers, activating Wrath after contact for a 1shot. This will also provide big chunks of damage against bosses.

For the Shotgun, firing both barrels will 1shot anything not in carapace so long as you're proccing Full Bore. Don't get fancy - bodyshots on Maulers and Ragers will do, and you can spam them out pretty fast to deal with stacks of them. For Ogryn enemies you'll need to be careful not to hit their carapace parts (the heavy metal bits of armor). Aim for the heads or the arms side-on for Reapers, and most Bulwark attack animations will leave their bare torso exposed if you bait them out and dodge.

Throwing knives are a very efficient and necessary pickup to deal with specialists at range, so long as you've practiced landing headshots enough to manage it more often than not.

Don't be afraid to spam Wrath especially if you've got both charges available. With your crit rate you'll burn through the cooldown very fast and the additional attack speed is great to have up to reduce the delay on Eviscerator lights as much as possible.