"Chaotic Good" Support Knife Zealot
Build for Darktide

"I cannae let these humble servants of the god emperor leave his service just yet."

Pros: 

• Extremely high winrate build that prevents your team from taking damage and is extremely versatile. 
• Works especially well in squishy teams (vets and psykers)

Cons: 

• No Until Death or Thy Wrath be Swift, so no crutches for bad play on your end
• Chorus doesn't play well with Smite Psykers. 

If you play this build right, you're sticking with your team and encouraging them to stick with you. 

Works great with any weapon with critical bonus or finesse stat that uses light attacks against hordes. 

TIPS

Use your speed to clear flanks as you move forward so that your backline can do their jobs untroubled. If you don't then all the trash you left behind will go attack them in addition to specialists and whatever else spawns behind the team. When that happens, best case you get no support up front and worst case they go down. Check on them occasionally and use your speed to return quickly if they're ambushed. If there's no flanks that need clearing, stay in coherency since you don't have loner. 

To make use of Emperor's Bullet, you can keep the kantrael shotgun empty except for 1 special ammo shot. Shoot the special shot and reload it immediately then switch and enjoy your melee buff for 5 seconds. Repeat in combat whenever you have a good shotgun shot. If you're using it for this purpose, ammo is not an important stat. This is optional, and you may prefer to keep the shotgun partially or even fully loaded in between fights to dump 4-9 shots into a pack of ragers. If I have plenty of ammo, 4-5 shots loaded is a good middle ground. This also works very well with a Zarona Revolver with Crucian Roulette. Use that if your melee isn't great against armor. 

Against Ragers, 1 throwing knife to the head will weaken them and a single heavy attack will finish them off and refund your knife. Shotguns are also great at staggering them. 

Against Bulwarks, you can use shotgun flame shots while their shields are up to get burn stacks on them and trigger Emperor's Bullet, then a single heavy headshot while they're attacking will typically stagger them and make them easy to finish off. 

Knife

There's several combos of knife blessings that work great. 

Executor, Flesh Tearer, and Riposte are all great. You don't really need high bleed stacks from bleed blessings, but it's nice to be able to quickly reach max stacks with 2 crits when fighting a boss then put some burn stacks on them. Uncanny Strike is the best blessing because you can wrack up weakspot hits really easily which will slightly increase horde direct damage and allow you to bury maulers and handle crushers faster. 

Crit perk on knife is nice but Maniac is great too. When you need crit, blazing piety will be active. When it's not active, you'll be fine. Crit perk mostly helps with Crushers/Maulers and Bosses. Maniac can let you get the Mutie 1-shot if you successfully dodge and have high first target.  Besides Flak, Crit chance, and Maniac, few others will make a significant impact on play. Unarmored/Infested can become a detriment as you can't increase your crit chance by hitting bleeding enemies if roamers/poxwalkers are dying in a single hit. 

Kantrael Shotgun

For Kantrael, Scattershot, No Respite, Flechette, and Deathspitter, Fire Frenzy, and Man-Stopper are all perfectly good blessings. Flechette is particularly nice in this build because it will get bleed stacks on a large number of enemies, giving you tons of melee crits, but it and Man-Stopper are only recommended if using Scattershot. No Respite is great if you prefer keeping the shotgun fully loaded and blazing down all the shots at once, and Fire Frenzy and Deathspitter have good synergy with it. 

The flame shot on Kantrael Shotgun is limited to 10 stacks of burn, which isn't super high dps but will help with a boss. It gives a maximum of 6 stacks in a single shot to 1 target, so against bosses you should do two special shots, unload the magazine, one more special shot, then melee for a few seconds and occasionally do another special shot to extend burn and trigger Emperor's Bullet. 

Alternatives

Thy Wrath Be Swift

It's really good, especially if you don't like getting stunlocked by shooters. That said, you get uninterruptable already from Punishment pretty easily and you'd have to give up Sustained Assault or Duelist for it. Also gives Dance of Death which has interesting interactions with shotguns, but can be annoying when you're trying to light a wide area on fire. 

Pious Cut-Throat

20% CDR on backstab kill is insane on pretty much any build and can let you chorus before the buff from the last one even fades. Keep in mind that stagger and dodge are good ways to get backstab kills in a horde. I think it's overkill but still fun. Keep in mind you will probably have to give up Duelist and 5% speed for it. 

Other Shotguns:

• Lawbringer VI is an acceptable substitute to the Kantrael, and really favors Flechette. 
• Agripinaa IX (slug) is a decent option. With Man-stoppper the slug can pierce 20 enemies, but that's a lot less useful in practice than it is on paper, mostly because the shotgun is awkward to aim when switching to it, dodging, or moving.