Barrage Psyker: Electro staff primary / Assail / Disrupt Destiny
 Psyker Build - Warhammer 40k: Darktide 

Overview

I originally wrote this build when the Channeled Force and Empyric Shock talents were first introduced, and tried to find a use for them along with Malefic Momentum. At that point, it was fun to play, but couldn't compare to meta builds. After the Bound by Duty patch, the build is significantly improved, and very capable of difficult content (certainly Auric Maelstrom, I've only tested to mid-20s on Havoc).

The build has a fun, engaging, and aggressive playstyle that is constantly swapping between all the tools you have, with high movement speed for positioning. A big focus is the Nomanus Mk VI Electrokinetic Force Staff primary attacks. With this build, the staff's crit rate is between 50-70%, so the Surge blessing alone more than doubles the DPS. The staff also has a very high base crit/weakspot bonus, which gets extra benefit from Disrupt Destiny, along with Channeled Force and several other big damage buffs. Although this attack is weak against carapace, and doesn't do full damage against unyielding, it does full damage to everything else, including flak. Empyric Resolve, Battle Meditation and Solidity allow for a constant barrage of these attacks. Along with the DPS, this is great for suppressing enemies without costing bullets.

The build is an all-rounder. Assail and melee buffs tear through hordes and groups of low-armor elites and specials. But it's especially strong in the mid-range with the staff primary fire taking down elites and ranged, and the secondary attack keeping groups of carapace staggered. Empyric Shock helps with boss killing and tankier enemies. It's also solid defensively, and has a lot of team utility and CC (Telekine Shield, suppression, lightning stagger).

Playstyle

Close range low-armor hordes: While in melee, quickly swapping to use assail a few times helps clear the horde, keeps up stacks of Malefic Momentum, and keeps peril high enough to get the benefit from Warp Splitting, Warp Rider and Unstable Power. The staff primary attack can't pierce, so assail is valuable for killing specials or elites hiding behind a horde.

Mid-range hordes and ranged enemies: This is the specialty of the build, constantly shooting primary fire to take out most enemies, and keeping them suppressed and staggered. Every ~5 sec, use the secondary to keep up the Channeled Force buff. With speed buffs from Mettle and Disrupt Destiny (and using Telekine Shield if necessary), you can close the gap to hit priority targets easier, and reposition after. Trying to keep up Malefic Momentum stacks by switching to melee when you can is also valuable, while also focusing on disrupt destiny targets.

Crushers and Bulwarks: With a large group, chaining staff secondaries to keep them stunned (and hitting a primary shot every so often to keep up Channeled Force), then finishing off when appropriate with melee. For individuals, hitting max stacks with Empyric Shock then chaining secondary attacks is worth it. The Electro staff secondary attack is not as strong in this build, since it cannot get weakspot hits, doesn't benefit from surge, and we don't take Warp Flurry. But being able to keep them locked down and having strong melee helps with this.

Bosses: For monstrosities, weakspot staff primary attacks while keeping up Channeled Force is the highest DPS, and can be done far away. Melee is generally best for captains, though the staff isn't too bad. FYI - the twins have carapace helmets that should be avoided.

Alternatives

There isn't a lot of flexibility, some changes would defeat the point of the build. There are some tradeoffs that can be made though.

Talents: 

• Swapping Prescience to Seer's Presence may be better for the team in high Havoc. It's tough to give up on crit though: I believe a 5% crit increase ends up adding over 25% DPS on staff primary fire with 15 Disrupt Destiny stacks.
• If you are able to keep up 25 stacks of Disrupt Destiny, swapping to Perfectionism and Cruel Fortune is a huge damage increase. It is definitely possible to get to those stacks, the problem is keeping them, especially when you need to focus on higher priority targets. This is too inconsistent and you're less likely to have full stacks when you need them most IMO.
  • On higher difficulties, it's not too difficult to keep stacks high with Lingering Influence, but it depends. If this is a problem, adding Cruel Fortune would be worth it.
• The least critical talents are Warp Rider and the extra Stamina Boost. A more defensive alternative is swapping to One with the Warp, then either Ethereal Shards or maybe a toughness regen talent.
  • I picked Just a Dream over One with the Warp on this build since it impacts both toughness and health damage, and the peril increase downside is reduced by the -50% peril reduction.
  • Per kuli's Psyker talent breakdown on Steam, Warp Splitting is better than Ethereal Shards for assail piercing at peril >50%, while also affecting melee. The improvement from adding Ethereal shards is relatively minor for a build not focused around Assail.
• Usually True Aim is not great, but due to the the extra hits from Surge and piercing Assail, it works out to a decent crit rate increase for high weakspot hits. Since this maxes out after a bit of melee, this also can help ensure an assail or staff secondary crit. IMO Kinetic Deflection is more valuable though, especially since this also benefits from the peril reduction.

Melee weapon: This is up to preference, but the weapon should be strong against carapace, at least decent at horde clear, and should have a high crit chance and crit bonus. The Covenant Mk VI Blaze Force Greatsword fits this criteria very well. The force push and stab is particularly good against groups of crushers, and it also benefits from maintaining high peril with Unstable Power. Lightning Speed and movement speed buffs from Mettle and Disrupt Destiny help with the downsides of the weapon. Alternatively, the Maccabian Mk IV Duelling Sword also works great, even after the nerfs to Carapace damage and finesse.

Ranged weapon: Not much can change here. If you wanted to sacrifice Carapace damage for boss damage, you could maybe swap to Unyielding.

Trinkets: A lot of flexibility here. My general thinking is that there is that high toughness helps counteract the Empyric Resolve toughness debuff, and since Just a Dream affects health, having at least some +Health has extra value. Stamina is a bit less important with Kinetic Deflection + peril reduction.