Shivs Smackdown ( Havoc )
 Hive Scum Build - Warhammer 40k: Darktide 

Build Alternatives :

1. If you aren't as used to dodging in close quarters, replace Nimble with Alley Rat to gain more distance on each dodge.
2. If you have a Veteran with Survivalist on your team, replace Pickpocket with Channelled Devastation for higher melee damage.
3. If you get hit often by small melees, replace Forge's Bellow with Street Tough. You will loose out on much higher controlled stagger against monstrosities and ogryns for the net gain of never being hit twice in a row, effectively never losing health to smaller melee enemies.
4. Forge's Bellow can also be swapped for Chem Fortified for more constent toughness.
5. Stripped Down on your Branx MKII Needle Pistol is amazing at being completely immune to range damage if you know how to run slide towards enemies, the sliding animation allowing you to regain staminna and is still considered running, which will keep the blessing active. If you have a harder time doing so, or managing your stamina as a whole, swap it with Ghost, making you immune by chaining weakspot hits. ( keep in mind both perks will make you immune to Reaper fire, Scab Captain plasma and Scab Sniper shots. )
6. If you desire to rely more on crit chance, rather than finesse ( giving yourself more crit damage and weakspot damage ), replace Precognition on the Improvised Mk I Shivs with Riposte.
7. If you want to fully use your stimm lab points, you can take Spur V ( Both immunities are as of now bugged and aren't working but you will still gain 4% attack speed ) or Fervor  ( but considering the best utilisation of this stimm in line with this build, you will not see a significant boost ). All in all, you have th choice to add a point, but i wouldn't advise for it.
8. Both Variant of the Needle pistol have there use. The Branx MKII Needle Pistol pack 6 chem stacks on primary fire body shots ( 7 on headshots ) and it's secondary fire pack 3 chem stacks but will explode and propagate to the enemies around it once the target dies, making it a strong option for horde clear if ever needed. The Branx MkVI Needle Pistol pack 7 chem stacks on primary fire body shots ( 8 on headshots ) while the secondary fire pack 4 stacks and will explode doing higher damage to nearby enemies but won't propagate the chem effects.

Strength :

• You have the most important and consistent single target damage in the game ( even so you will not one shot bosses like the thunder hammer. ) your TTK ( time to kill ) against any and every enemy in the game is ridiculously low. The combination between Improvised Mk I Shivs insane armor pen and single target damage + crit ratio, Rampage! gigantic melee boost, Channelled Aggression free rending, Chemical Dependency crit chance, Hyper-Violence damage stacking, Hyper-Critical instant kills, The Sweet Spot large damage boost for Improvised Mk I Shivs and stimm use giving you finess and attack speed every 65s, ( to which you could add Channelled Devastation if you have a veteran on your team ) make you an insane melee attacker capable of handling any significent threat coming your way.
• Even while not nearly as horde clearing as other setup would, Pulverising Strikes while under Rampage! will allow you to easily deal with any hordes. Additionally Rampage! effect duration is kept up by Boiling Blood making it active for the most important part of your fights. Splash Damage will also contribute to clearing hordes with ease.
• The Branx MKII Needle Pistol give you the best range option used as secondary in the game. Chem stack can deal with basically every enemies on it's own. You can also do immense constent damage to monstrosities by stacking 30 chem stacks on them before meleeing ( which on crit will reaply them ).
• Swift Endurance will allow you much faster melee reaction with higher attack speed ( 20% at full stamina ). Meanwhile Hive City Brawler will synergise directly with your stamina utilisation, giving you both damage and defense.
• Forge's Bellow will allow you to knockback any enemies in the game ( boss included ) at both end of your Rampage! utilisation on a 30s cooldown. Making you able to create space where you otherwise wouldn't be able to.
• Sample Collector paired with Coated Weaponry will allow a constent usage of your stimm ( which directly impact your constant 3 stacks of Chemical Dependency ) while Blessed Stimms will maintain you without corruption ( important considering you already have not enough health ! ). The fact that you're a hive scum will also directly impact the stimm economy and usage of your team. 
• You possess very high mobility with Nimble paired with the high movement speed and reactivity of both the Improvised Mk I Shivs and Branx MKII Needle Pistol.
• Boom Bringer are the best grenades in the game, allowing you to counter any and every situation. You also have more of them due to Extra Pouches. Any team that have this detail in mind will let you basically get every grenade for priority, allowing you to use it often even without any regen perk in thetalent tree.

Weakness :

• As you aren't using Chem Fortified, and even while taking into account Burst of Energy and Tis but a Scratch you stay squishy. In fact, as this build is very offensive in the way it was made, your survivability comes from your constant dodges, good positioning, understanding of stamina use paired with Stripped Down and Hive City Brawler, a hit will very easily do half your health, and two hits from small enemies will do the same ( you do not have Street Tough against this ). One mistake can easily bring you down, as such it is more skilled intensive than most builds.
• You aren't using Battering Strikes which will make you weaker against hordes than a build that does have it.

Conclusion :

More than 95% of builds on this class and all other classes, this build is the typical " get gud scrub " build. If you play well, you have one of the most powerful builds at your disposal to wipe the floor with basically everything and even clutch harder situation. If you do not play well or understand how you're supposed to play with it, you'll have too much of a hard time to sustain it and will die a lot, impeding your team, even while taking into account the 4 shots of Boom Bringer that you will inevitably used in stressful situations. Stressful situations that will happen a lot more for you if you do not play well with it. 

All in all, one of the strongest melee build you can make on this class. Will actively carry havoc, even against Rotten Armor, and will push you to your limits, making you a better player the more you play it due to the no room for mistake with high carry potential.

Extremely fun ! 
Is using the 2 most meta weapons of the class ( i'm sorry, that is indeed a change from the other ones i made ahah ) 
but worth a try, worth a learn, and worth the fun !
 

I encourage you to try it out and tell me what you think ! ;)