Sword Scum (tanky)
 Hive Scum Build - Warhammer 40k: Darktide 

Overall, this is a fun setup I've been using for the scum which focuses on tankiness and survivability while still outputting solid damage.

For blitz, you could swap out for any, I just like big explosions, plus the immediacy of it makes it useful as an uh oh button. It is also nice that it staggers bosses too. 

For our ability, even though we are mainly a melee build I prefer Stimm Supply over Rampage due to Rampage having a massive drawback when it ends. Even though you could do more damage on rampage, you can make up for it by supporting your team. You can either cycle it with your stimm which is what I do most the time or stack them for greater effect when you really need it.

Chemical dependency is a great keystone and with Stimm Supply we can keep it active easily even with maxed out chems so long as you make sure to stimm before using your ability if they are both off cooldown.

For our stimm, cooldown isnt a worry so we get a bit of everything else. You could certainly customize it if you prefer other options but since the point of this build is to be tanky going up to Barrage IV is the most important. You dont really want to go much past that though since compared to all the other nodes and especially Barrage IV, the returns are quite diminished for such a high cost. You regen 75% tougness thanks to the bonus from Chem Fortified which is typically enough that you can get the rest back on your own even if you are at 0%. Note that toughness regeneration from this is referring to your coherency toughness regen which is why I put it on my curios since it gives a lot of regen which makes a difference when you catch a break and have no enemies to hit in melee. It just means you have to play with your team and keep them alive. 

The devil's claw sword is great because it can completely counter aggressive enemies like ragers with the parry ability and will even block crusher and mauler overheads in a pinch, though it can be a bit finicky so be careful. Try to time it right before it hits, because otherwise it might not work or will consume all your stamina. But thanks to hyper-violence and hyper-critical, your heavies and parries can do a ton of damage when we crit so we want as much crit potential as possible. For stats, you can dump cleave targets or split it with mobility in favor of mobility since we make up for it with our blessing devastating strike.

The needle pistol is a very unique weapon that is good against everything, only limited by its low mag size and that it takes a moment to kill. But this makes it a perfect sidearm since it can deal with all our problems, especially crushers and it will delete hordes when you switch to blue mode. It is also great against bosses since you can start that toxin on them from a distance and then maintain it through criting in melee. Or even just keep those stacks on them and keep running in circles, most useful for Beast of Nurgle. The blessings aren't as important on this weapon since the damage is mainly coming from the toxin, so I go with stripped down and run n gun for the utility. Run n gun can be swapped if you like but I prefer it since it makes your hipfire a bit better. Note that it takes only three shots to kill crushers meaning you can kill two per mag though it wont be quick, so you can mag dump them if you need them to die faster.

Hope this works for you and have fun!