Desperado
 Hive Scum Build - Warhammer 40k: Darktide 

Playstyle:

Literally the only thing this build is for, is to go dakka dakka in pure hive scum style! 

It's a basic support that any team would love to have you in with the front liners. You have two plays with this build. Firstly, you are the best at taking out all of the ranged units because you can not be touched by them, but also very heavily anti-flak. Yes, especially Ragers (both!) and Maulers. You will heavily struggle against Brawlers though as their shield completely counters the SMGs. You will want to spam ranged as much as you can within your ability but do not worry about running out of ammo. Your ability gives you two magazines back, for free! Not only this, you do not use ammo up as your ability is active. Ammo is shared among the aura radius. Secondly, you completely counter all ranged units in the best way possible. You can not be touched by them whilst you have your Enhanced Desperado up or as you keep dodging around with your mobility. So, see a room full of gunners holding down the doorway? Ok, now tell your team to wait, activate your ability and run into the room guns blazing at every single ranged unit. Murder them or catch their attention so that your team can follow up with you second later and then they will replace the front line with you.

Do remember, you are targeting specific targets. Maulers, Ragers, Mutants, Hounds and Trappers. A group? Spam it with bullets! 

Weapons:

Branx MkIII Dual Autopistols is your main go to here as that is what the build is literally built around. What you want to do is spam them as much as you can (within reason!). They deal semi-decent damage, but they fire fast and the accuracy is not bad at all for such a high fire rate. You can easily control the spread at times by being up close but also but literally bursting the first few bullets for longer range. Leave it 0.5 seconds to return back to normal and burst again. This is only if you require to take out Scab Sniper at a distance etc otherwise focus on the rest. All you are doing is using them to keep your stacks of ability going for as long as possible whilst decently killing everything. So the downside to the weapon is actually the reload and it is not the best outside close combat in terms of base stats (like armour piercing). I like to focus on Maniacs over Carapace because the Carapace damage reduction is too high, even with rending. Mutants, ragers etc are my go to to help the team with clearing and not having to worry about. Carapace takes too long to kill and it wont reduce enough time to kill them over ragers which spawn in massive groups currently. Other classes/builds are better off taking the anti-carapace role.

I like to choose the Improvised Mk I Shivs as my go to melee weapon. It allows me to be faster in the melee where I can not shoot but it allows me mostly, to handle carapace armour. The heavy attacks are great for targeting the head for maximum damage. If your ability is down, or you got no ammo, you need an efficient melee weapon to handle everything. The hive scums best melee weapon for that is literally this. Do not use the Chirurgeon's Mk IV Bone Saw ! The attacks are way too slow and not only this, the weapon focuses your aim on the target on many of the attacks as you hit it. It counters your mobility too much and wave clear. 

Cruios:

Best to stick to the weakness of the Hive Scum, toughness. I have been playing with 3x Stamina as well but it is not a requirement, but more a preference of the player. In general, a third Toughness would be best but the stamina allows me to have more options for when things get too much.

Not only this, I am able to use the stamina to effect talents like Hive City Brawler Swift Endurance. It's good for a backup weapon like the shivs where additional stats are always helpful when you are so focused on your ranged. If you can't use the ranged, you need something to handle yourself for now until it is up again.

Talents: 

• In Your Face, Quick and Deadly and Speedloader is great for this build. Since you are supporting the front line, you are within range (haha, get it?) to murder everything up close. With your ability, you are already getting highlighted enemies to stack up more time on your ability usage total time, so why not buff the damage? It does make a difference on the SMGs as they are generally a low damage weapon, with fire rate. 
• Pickpocket, Gunslinger Improved and Enhanced Desperado together are amazing when it comes to ammo efficiency. Not only do you get unlimited ammo during your ability, but you then share ammo pickups between those within the aura (yes, 10% can mean a lot, especially for those with high total ammo) and then you even gain even more ammo when you kill elites or specialis with your melee. This combos great together in almost every way possible. Something to add to your ability though, you gain rending. This is extremely important to max out your DPS to the best you can with the fire rate. What better way, then to completely ignore the armour? This is where I would suggest to focus where you aim. Main example of this is the Scab Mauler Do not aim for his head due to the carapace armour, except, aim for his body and absolutely destroy him in a few seconds maximum. No joke, you can kill roughly 10 Scab Mauler in a matter of 15 bullets roughly with ease. Obviously give or take with the horde and other stuff around too.This is where you support the team the most by focusing on such targets (Ragers, Maulers, Hounds and Mutants). Not only this, you can clear the annoying Scab Trapper with ease by ripping through hordes and killing them in the crossfire. Support your team and focus the correct targets!
  Best advice I can give when you are using this ability, spam everything you can. With the reload buffs you get from Speedloader you can spam, reload, and keep spamming. You want to kill as much as you can, especially the lesser hordes. Everytime you kill, you extend your ability more and more. Not only this, you supress the enemies around you. You will end up laughing at times where the enemy is screaming "No, don't kill me!" whilst waving his hands as you mow them all down.
• Now lets talk about the blitz. I believe there is literally only one solution for this and i'll explain why, but that is the Blackout. Before you judge, hear me out. The point of why this build works is because you keep your threat up high the more your ability is up, right? Both the Boom Bringer and Chem Grenade both do the opposite to what you want. They both kill as fast as possible, or instantly. You can not stack up anything with this. So, using the Blackout as a support tool is your best option but mostly, not for you, the team. Yes. When the moments get hairy, or doorways are not able to hold by the tank or frontliner, you literally throw one down. Instantly, everything but Crusher and Bulwark (not including any bosses) will stagger to the floor. Guess what happens next? Murder from you and your team. This is why I feel the blitz is super strong because not only this, you have unlimited grenades. You generate a grenade every 20 kills within 12.5m from you. This is your strong suit and why even more you support the front liners.

Stimm Labs:

I went with a fully standard set of use for the Stimms. 

• Ability cooldown - You want your ability up as much as possible.
• Strength - Works in both Melee and Ranged. Go nuts with bonus damage and stagger.
• Rending - Sooo important. You want to stack your rending for in and around your ability. You can use this just for the rending outside of your ability OR you can stack it with your ability for evern more Rending. I suggest to not always stack them unless you require too (massive armour stack spawns).
• Swap Speed - This is important for when you have to sometimes mix between Melee and Ranged. 25% may not sound like much, but remove it and test for yourself. 

Remember, the more points you put into this, it increases the cooldown of the Stimms so you want to restrict yourself to a reasonable cooldown. This is to me is a standard of 60 seconds. A lot can happen in that time, especially as your ability is every 45 seconds for cooldown (this is not talking about extentions).

If you find any issues with this, I am always up for suggestions but please respect opinions of how it is played, and if not agreed upon.