SwiftPossom Hive Scum
 Hive Scum Build - Warhammer 40k: Darktide 

Gotta go fast. Melee the trash. Traveling with the shivs out is great for farming loot. 

This is not a front line/tank build. 
Use the slides/dodge/block/push/nades to prevent as much damage as you can.
Use extra dodges for those overhead smashes from elites.  

Using the ridiculous dodge distance in melee for fast traveling and running laps around your team to cover basically every team member and/or rush objectives. 

I don't recommend being the one carrying objectives or solving puzzle unless you have to.

Get familiar with how many shots each Elite/Special takes with the needle gun, this build somewhat helps with ammo but wasting ammo is the only thing that will make this build very sad. If you need to kill things faster and your ammo is topped off, then be a little more liberal with shots. I generally empty or almost empty mags against crushers and bulwarks. 

Only melee kills on specials will replenish throwing knives. They are useful so practice getting used to them and replenishing them if you can do so safely.
 
Drop Stimm supply at choke points.

Needle gun tips.
Prioritize crushers bulwarks ogryn gunners/elites/specials. Try not to waste any ammo on trash. 
It's without saying you should prioritize the biggest risk. Don't panic and realize that trappers, mutants, hounds are game over in high pressure situations so take them out then go back to focusing priority targets. 

When things get sticky use your Blitz Blackout Grenade Extra Pouches and Pocket Toxins are great for crowd control and clearing out trash if melee is taking too long. It's also great if the hordes of elites are taking too long to clear out. This build gives you 6 and they replenish for every 20 kills. I also like to throw a nade at a downed ally and needle gun the elites with a couple of shots as I approach for the revive, this usually gives enough time for the save. 

As much as I love the other blitz nade and launcher. Having a limited supply and relying on grenade loot can result in sadness. 

Since the mag is pretty small you're gonna want to reload often, don't walk around with 1-3 rounds in the mag, it's just better to move with a full mag. 

If you're in a clutch situation, rely on the speed and agility of the build to create space for you to save your hostage allies. You can basically make them chase you very far from the revive site and then use the ridiculous side dodge distance and speed to buy you time to save one or two before the hoard catches up. I've even gotten away with this against some monstrosities. 

Do your research and realize somethings do direct health damage. 

Good luck have fun  and of course calibrate the build to your liking.