[In-Depth Writeup] [Traitor Curse Part 2] Auric Maelstrom Helbore Mk3 Vet
 Veteran Build - Warhammer 40k: Darktide 

I am an exclusively Auric Maelstrom (Waves of Specialists modifier minimally) or Auric High Intensity - Shock Trooper Gauntlet (HISTG/HiShock) player (in the case where the Maelstrom has no Waves of Specialists modifier). I have close to 2000 hours across both Vermintide 2 and Darktide. My builds are the product of extensive testing, both in the field at the highest difficulties possible, and in the Psykhanium. 

This build has been played extensively at the Auric Maelstrom level as of Patches 13, 14, 15, Traitor Curse (both parts), with considerable success. 

Overview

Traitor Curse Part 2 reworked the skill tree, giving us more points to work with.

The Helbore is very much an acquired taste, even at its peak in Patch 13. Its slow pullout time and long initial charge up means that players who are used to other guns being able to respond more quickly to specials will find the Helbore jarring to use. Playing the Helbore requires a change in attitude and playstyle:

1. Firstly, you need to be able to have your Helbore out most of the time rather than have your Melee out. This means that you need to be good at quick swap to melee and block and dodging on ranged weapons (always dodge at the last second to stop the enemy attack tracking), precise management of dodge count (because you won't have a lot of dodge count with a ranged weapon).
2. Secondly, you need to adopt a mindset where horde/elite stragglers in front of you are shot rather than melee'd. Typically, you would melee hordes or lone elites to save ammo. The Helbore Mk 3 can go ammo positive across an entire mission even without picking up ammo, because of Shock Trooper. You do not use the Helbore's melee option either, you shoot to stack Onslaught.

By playing as per above, you can increase how much you have the Helbore out and firing, which means that:

1. You can skip the pullout time of the Helbore if you already have it out.
2. You can stack Onslaught in preparation for when specials come out.

And yes, in case you're wondering, you need to adopt this mindset and be good enough at ranged into melee combat at the Auric Maelstrom level to be able to play this weapon well. This weapon build has a higher skill floor than Plasma, Revolver, Autogun or Laspistol.

Helbore Mk 3

We start off with the Helbore Mk 3 in the ranged slot. The Helbore Mk 3 boasts the capability to one-shot headshot almost anything in the game without crit, and with crit, it can hit some obscene one-shot bodyshot breakpoints. The hard to hit breakpoints would be the non-crit one-shot headshot Flamer breakpoint if your Helbore Mk 3 is not a god roll (80 damage, 80 stopping power, +25% Maniac), so we use Focus Target keystone to add the extra few % of damage to hit this breakpoint. Marksman's Focus is also viable to add the extra few points of damage, but it's less consistent to stand still (requires a slight playstyle change) to start stacking Marksman's Focus vs. just pinging the Flamer and lining up the headshot with Focus Target. Weapons Specialist isn't very good for how the Helbore should be played. I explain it in the overview section, but you really want to have your Helbore out most of the time.

Plasma is really the top end of the meta right now with a similar or better damage profile relative to the Helbore Mk 3, but has 100 cleave, the ability to deal with Bulwarks, and little to no pullout time. So, what is the advantage of the Helbore over Plasma? 

• Helbore has practically no ammo consumption at all, while the Plasma guzzles ammo. In missions with multiple ammo-intensive weapons like Gorgonum, Columnus Infantry Autogun, etc, the ammo load can be so high that Survivalist and ammo pickups can barely keep pace. Helbore improves the ammo economy of the team.
• Helbore has better sustained performance. The Plasma starts out really strong, but starts to suffer because of its heat mechanic. The heat mechanic is not a super big deal, but it does exist. The Helbore is the opposite - it starts off slow, but it ramps up with Onslaught to the point where it's firing about as fast as the Plasma's uncharged shots, with a slightly lower damage profile, but it can keep going because of Shock Trooper nullifying much of the ammo consumption.

However, I will still say that despite all this, in my view, Plasma is still overall stronger than Helbore right now, so you picking Helbore is really because you want to play Helbore.

The perks and blessings are incredibly standard. 

• Maniac lets you hit one-shot bodyshot on Trappers and one-shot headshot on Flamers with a bit of extra damage from Focus Target. 
• Flak lets you hit headshot breakpoints on Gunners and Shotgunners.
• Onslaught is the best-in-slot blessing for Helbore, letting it ramp up in a fight. -60% reducing charge time is bonkers and lets you light up the kill feed if you aim is good.
• Surgical with the buff in Patch 13 is so strong right now for almost every ranged weapon that can have access to it, and it synergises very well with the Helbore Mk 3 because of the charge up and Shock Trooper. Crits can turn headshot requirements into bodyshot requirements, and reduce the overall number of shots to kill.

Mk 6 Power Sword

The Power Sword was actually secretly the best melee weapon in the Vet's arsenal in Patch 12 and 13, and it got buffs in Patch 14 that really pushed it even further. However, this status only applies if you're very good at the melee game. With a poor dodge distance and dodge count, the Power Sword heavily punishes uncontrolled and poorly timed dodging. However, if you can play at the minimum level of melee skill required, the Power Sword has by far the best horde clear in Vet's arsenal, top tier Maniac DPS, one shots Dogs, and can kill Maulers, Ragers and Crushers in mixed hordes easily. The skill floor is high, but the performance on the weapon is essentially unmatched. 

What's the issues with the other weapons?

• Combat Axes: Poorer horde and elite clear, especially with the reliance on Brutal Momentum to even cleave, against Mixed Hordes with Maulers/Crushers you cannot hope to cleave the mixed horde in the same way that a Power Sword can.
• Sapper Shovel: highly defensive, poor damage output.
• Catachan Mk 4 Devil's Claw Sword: Garbage flak damage output, poorer horde clear, and because of the poor flak, struggles to clear Mixed Hordes. The parry is really just a gimmick against Crushers, it doesn't deal meaningful DPS to matter against Crusher packs. It's good into Ragers, but the Power Sword also shines into Ragers.
• Munitorum Shovel Mk 3: still not great damage output into hordes.

Take it from me that if you struggle on the Power Sword in melee, it's not a Power Sword issue, it's a skill issue on your part. Rather than blaming the tool, learn how to melee better:

• Many people screw up when to Energise. If you want to Energise while fighting a horde, Energise and then dodge. Do not dodge and Energise. This is because the dodge tracking immunity does not last long enough to cover the Energise duration.
• When do you dodge? If you're dodging constantly, you're doing it wrong. Dodge only when you hear the sound that you're about to be hit, if you want to use a heavy attack, or to Energise. 
• Which direction are you dodging in? Dodge mainly in one direction, don't dodge left right left right, because that nullifies the tracking immunity every time you return back to your normal position. If you want to switch your overall dodge/kiting direction, mix in a block/push.
• Are you dodging correctly against Poxbusters? Because of the poorer dodge distance of the Power Sword, sloppy backslides and dodges against Poxbusters (sliding back diagonally) will cause you to still get hit by the explosion. Learn how to precisely input only back dodge/slide.
• When do you use lights and heavies against hordes? Light spam is safe but not max DPS/horde clear, so mixing in heavies will increase your horde clear speed. Furthemore, heavies deal well with Ragers/Maulers in the horde. Ideally, use the following chain post-Energise: Light 1 > Heavy 2 > Heavy 3. Do not use Heavy 1 unless you have space, because you'll need to commit an extra dodge post-Energise to open up space to use it. Heavy 1 is most useful when you're far away from a pack of stragglers, elites or Mutant, and you can Energise, slide and heavy 1 the pack/elite/Mutant. Post Light 1, because of the insane cleave and stagger of the attack, you'll naturally have some space to use a Heavy 2, but if you hear the hit sound, you can either opt for Light 2 or go for dodge into Heavy 2. Similar logic for the Heavy 3.
• When do you use the Push Attack > Overhead Combo? The DPS of the Push Attack > Overhead combo is actually only slightly better to that of just using lights/heavies, but it only targets one enemy. Use it if you're duelling a Crusher or Mauler 1v1, but in a horde, use Energised lights/heavies instead, it's not entirely safe to use single-target attacks in a horde.
• How do you kite when melee'ing? Do you actively try to keep enemies in front of you? How are you moving vis-a-vis your team?
• When do you mix in blocks and pushes? When you're trying to change kiting/dodging direction, when you're running out of dodge count.

With regards to which Mk to choose, the Mk 6 is the superior option right now. Straight line cleaves on lights help to relieve pressure if you can't heavy because they have better cleave profiles (it's easier to headshot on straight line attacks) than the diagonals of the Mk 3. The Mk 6 has the option of Push Attack > Overhead Light which the Mk 3 does not have access to, and the Mk 6 has innate 25% block cost reduction as well while the Mk 3 has none.

There is some debate online about the blessings to take for the Power Sword. Perks are straightforward:

• Maniac increases your DPS into mutants which are incredibly important to dispatch quickly at close range.
• Flak increases your DPS into Maulers and Scab Ragers, as well as the bulkier parts of a horde (Scab/Dreg Bruisers).
• Slaughterer is the premier pick. Some people will say that Slaughterer doesn't let you hit better breakpoints on hordes. It does however, let you hit better breakpoints into elites in a horde, which is incredibly important.
• Rampage actually increases Power, not damage. It gives close to Slaughterer level damage/cleave into hordes, but activates in a single swing into a pack (so slightly faster than Slaughterer). However, Slaughterer will still edge out Rampage against loose packs, and still performs slightly better.
• Brutal Momentum actually improves damage against hordes more than Slaughterer, but you're sacrificing your mixed horde clearing power for it, because the Power gain from Slaughterer is important to kill elites in a horde.

Build

We go for Confirmed Kill as Exhilarating Takedown is still bugged, and even with Confirmed Kill being nerfed, it's still a strong source of toughness against Gunner packs.

Krak Grenades are very strong to eliminate/soften packs of armoured enemies and Bulwarks. You can still use them like Frag Grenades in a pinch, but they have a longer fuse timer. They also can chunk bosses. You don't need the Grenade Tinkerer's enhanced damage, because the Kraks can already one-shot Crushers and Bulwarks without the upgrade, but if you have a spare point it's very much worth considering to chunk bosses harder, soften entire packs more and to deal with Nurgle Blessing Crushers/Bulwarks.

Catch a Breath is stronger in shootouts, while Get Back into the Fight can be strong if your melee skill is still lacking.

Survivalist is mandatory if you're playing with pubs. It's the reason why Vet is so highly desired as a one-of in a team. The difference in ammo economy at HISTG and above with and without Survivalist is like day and night. You're actively screwing over your team if you don't pick Survivalist. Just to emphasise how important Survivalist is, if this was a PvP game, I would report you for inting/griefing if I see you not picking Survivalist. The only exception is if you know someone else is already taking Survivalist, in which case, I would recommend going for Krak Grenades and Fire Team.

Demolition Stockpile lets you throw Kraks at your problems freely.

Infiltrate fits the Helbore extremely well. It lets you Stealth to take out your gun and take the initial shot (which has no Onslaught stacks) against a priority target, and following that, you can then take more Onslaught-empowered shots with -90% Threat. Stealth in general performs better than Voice of Command in terms of clutch potential and objectives. Voice of Command is still really strong even post-nerf, but Helbore has synergy with Stealth which is also very strong.

We take the +1 charge for better clutching, and the -90% Threat Profile which lets you continue to take shots in the middle of a horde as long as someone is taking aggro.

We do not take the toughness damage reduction as Infiltrate can let you reposition away from Gunners and Shooters, and we do not take the +30% damage bonus, as points are already scarce, and the Helbore does not hit anymore notable breakpoints even with the bonus.

We then path to Shock Trooper:

• Precision Strikes is necessary for some of the breakpoints. Deadshot can be strong but we don't have the points.

We then path to Focus Target to pick up the extra damage to one shot headshot Flamers non-crit:

• Tactical Awareness, Iron Will and Bring it Down are stronger than their counterparts.
• Redirect Fire is extremely strong, but we don't need the extra damage for any breakpoints ourselves, and our teammates may not play around the extra damage. Also, we don't have the points.

Curios

This is actually up to your preference. I would say Health is the most important, Stamina can be mixed in, and Toughness isn't too important because this build has 140 toughness.