Maximum Violence Scum
 Hive Scum Build - Warhammer 40k: Darktide 

This is my preferred melee shivs build. While Chemical Dependency is good, it requires a significant point investment and consequently sacrificing good nodes elsewhere in the tree, so I think Adrenaline Frenzy works better here. You can even skip Stoked Rage since shivs have high attack speed and crit, so you'll have okay uptime on Frenzy without any upgrades; however, Stoked Rage gives better uptime when enemy density is lower or when your teammates are getting a lot of the kills.

The build has enough melee damage bonuses that damage vs flak feels unnecessary on the shivs, so I opted for unyielding and carapace instead. For blessings, you want Riposte for sure since it gives good average DPS, helps proc Hyper-Critical more, and synergizes with Precision Violence and Adrenaline Frenzy. The second blessing is debatable, but I prefer Uncanny Strike because it gives better kill speed against crushers and maulers. Precognition is a good alternative since scaling finesse damage will allow Hyper-Violence to snowball faster.

I like bolt pistol in this build because it's better at sniping specialists than the needle pistol, and shivs already kill crushers fast enough that you don't need a ranged weapon that's strong against them. Bolt pistol also brings the Lethal Proximity blessing, which will increase your Boom Bringer explosion radius and also provide on-demand AoE stagger--useful for getting dogs off teammates or creating an opening if you get surrounded. I like Run 'n' Gun for the second blessing because it noticeably improves the gun's accuracy, but you could take Puncture instead if you like.

Curios are designed for Auric missions. Adjust as needed if playing Havoc or if you just want more defense.

The build doesn't have any sources of toxin besides the shiv special action, so I don't think it's worth spending 2 points for Extra Pouches.

Sticky Hands pairs really well with the bolt pistol for quickly picking off specialists while already engaged in melee, or making a quick shot to stagger nearby enemies. Sticky Hands + Run 'n' Gun gives respectable hipfire accuracy, so you can often pick off targets out to medium range without even aiming down sights.

There's a minor anti-synergy between Hyper-Critical and Hyper-Violence, but it's generally not worth worrying about in my experience. Hyper-Critical enables one-hit kills against more enemies and pairs well with the shivs' high crit chance. If Hyper-Critical triggers it won't contribute to Hyper-Violence, but there are enough enemies that die on crit without activating Hyper-Critical that you'll still scale Hyper-Violence at a good rate. Snowballing Hyper-Violence is mostly going to come from killing trash mobs anyway, while Hyper-Critical is more relevant to elite/specialist kills.