Miri Makes Meth Merrily
 Hive Scum Build - Warhammer 40k: Darktide 

There are a lot of really interesting synergies happening under the hood here. Your ultimate mission statement is to win fights for your team in a way that offers a lot of CC and safety while guaranteeing it gets more and not less manageable the longer it goes, and to be able to spot fix. You're more of an explosives expert than a conventional fighter in a lot of ways. 

- Your stimm is set up the way it is so that Practiced Deployment will replenish your Stimm Supply drop about ten seconds after Fast Acting Stimms makes it drop. The explosion it does will have its radius doubled by Lethal Proximity, and thus both stagger and poison more people, so try to have your pistol out when it goes off. This does mean you basically don't have a stimm, but no one said you were good at making meth. You apologize too much to be good at it. 
- Your Blackout Grenades are able to kill basically anything short of a Crusher pack with two throws when your pistol is out thanks to the fact Blackouts Stagger and your pistol gives bonus damage vs staggered when you factor in Pocket Toxin.
- You can keep the secondary poison for brittleness active on your weapon special if you'd like; Float Like A Butterfly, Anarchist and the +Crit node towards the bottom left of the tree should give you about 45%ish resting crit after every dodge, i.e. Coated Weaponry is applying more or less constantly, and taken with the stacks from your Blackout Grenades and exploding meth labs, you should be applying enough poison to justify going to Brittleness. Still, swapping them around every three or four swings at the same thing isn't awful either.
- You're squishy, but you do monumentally hard hitting damage on critical weak spot hits with the saw. Your pistol is also ideal for single targets if you use the default mark; end result, you're going to be using abilities for the hordes and weapons for singles.