40K SPEED BLENDER BUILD
 Hive Scum Build - Warhammer 40k: Darktide 

Update: look there is no way around this. You really want to play this class better? Install a mod that tracks stimm cooldown time, and custom hud so you can move the stimm icon near the center of the screen. When you have a decent chemical dependency uptime, then things will be better. This way you can actually have those 64 extra toughness points, 144 against 208, and get the attack speed that you would get from swift endurance from your stimm. This is a selfish class, and it will be performing well inside a team if you are greedy and play with top performance. 

Are you looking for a comfy hive scum build?
You want to play a melee focused Hive Scum build?
 This one will blow your mind for it's unicity, damage output and damage upkeep, and unparalleled survivability (at parity of skill level of the player that wields it).
This build presents oddities within it that are, however, easy to explain.

The blessings and perks on the needle gun don't work on anything but on the needle impact, while most of the damage it deals come from the chem dot damage. So it's your way to deal with crushers and bulwarks mostly, or! Far away dangerous enemies such as snipers or bombers. On top of that you have 16 stamina bars. S I X T E E N  with your needle gun out. Which means, that as much as you sprint you are basically immune to ranged attacks as you had Desperado active. Because your stamina is endless and there is no other way to put it.

Chemical dependency is currently the best keystone (even for ranged builds) and the idea is just to get a mod to have as much as you can 100% uptime on this. It's hard to track the stimm cooldown time without having any.
For instance: Adrenaline Frenzy is so bad that it gets outdamage by just the blessing Precognition on the Shivs.

Chem Grenade as it is the objectively best Blitz in the game at the moment, but after the buffs the rocket launcher can fit in a proper build, as a sort of a panic button useful for revives or when you get cornered for any reason. I would argue that the skill needed to use the rocket launcher efficiently is deciding on when to actually use it. The right moment could mean that you kill two times the number of enemies that you would otherwise.