Mez's Auric Psyker: Soulshrieker
 Psyker Build - Warhammer 40k: Darktide 

Overview

This build is all about setting up the Psyker as a tough frontliner that can flex in a number of different roles.  Soulblaze and Crit synergies across the talent tree and weapon selections give a lot of ways to keep your toughness topped off and keep you in the fight.  

Core Talents & Synergies

The Shred blessing on the sword, Prescience, base crit chance, Souldrinker, and the 5% crit chance node means you're hitting about a 43% crit chance with your Great Forcesword attacks.  Each time a crit procs, the sword applies more soulblaze stacks via the Blazing Spirit blessing.  This synergies again with Souldrinker. And of course Perilous Combustion is a further vector for Soulblaze.

Venting Shriek with Creeping Flames, combined with up to 6 warp charges from Warp Siphon gives you a rapidly refreshing ult ability, which also applies soulblaze, staggers enemies, clears peril, and can be pretty amazing for making space and turning the tide in a fight. And it refreshes quite quickly even without Seer's Prescence becayse of Warp Siphon.

Regularly switching between your staff and force sword, or using the Great Swords special ranged attacks, to build stacks of Malefic Momentum is great. 

This is also a HIGH PERIL build.  You can use the sword special attack or ranged staff attacks to quickly build up peril.  Warp Ghost is awesome for keeping your peril high, allowing you take advantage Warp Rider, One with the Warp and Warp Splitting.

Blitz Ability

With the changes to the tree, you can use any blitz you want and make the core talent path above work out. Brain Rupture with Kinetic Resonance is fun for popping your ult and quickly brain bursting a pack of elites at range while triggering Perilous Combustion in the process.  Kinetic Flayer got a nice buff with shorter cooldown and 100% proc chance.  It's an awesome and reliable damage spike now.

Personally, I find the utility value of Brain Burst in being able to safely kill snipers, catch fleeing dogs and trappers, to be well worth it over the other Blitzs.  But if you want to run Assail or Smite you can. BB is great for dealing with monsters and ogryns too.

Weapons Options

Instead of the Covenant Mk VIII Blaze Force Greatsword you can also run an Illisi Mk V Blaze Force Sword for much of the same effect. It's a bit faster swinging and has similar horde clear potential.  It's easier to build up peril spamming the special attack, but loses some of the wow impact potential of the greatsword's ranged attack.

In terms of ranged weapons, the Equinox Mk III Voidblast Force Staff is a great pick for both primary fire to delete scattered ranged enemies, and the charged blast attack for crowd control and dealing with bulwarks and crushers in the process.  You can of course go maximum soulblaze and take the Rifthaven Mk II Inferno Force Staff, which can be swapped right into this build with no issue.  

Options and Substitutions

You can drop Warp Ghost if you're diligent about keeping up your peril, although you also drop some stamina as well.  Instead of that, consider Vulnerable Minds, which is good for boosting damage against large targets, Perfect Timing to boost overall damage, or Empathic Evasion if you want to get some more ranged defense.

You can also play around with Soulstealer vs. Quietude. If you lean more on the Voidblast staff, and especially if you drop Warp Ghost, Quietude might be the way to go.