Mez's Auric: Psyker #5 Scrier Army Knife
 Psyker Build - Warhammer 40k: Darktide 

Overview: Scrier Army Knife

Like a Swiss Army Knife, this Psyker build brings tools for every situation.  It can put out solid damage, deal with point threats, and be reasonably durable (for a psyker).  This is a Crit-focused build relying on Scrier's Gaze paid with the utility of Empowered Brain Burst that can deal with special and elites across a range of situations.

Key Synergies

• Brain Burst can be used to great effect to deal with slipery specials (bombers at range, snipers, trappers, etc).  Using Scrier's Gaze with Empowered Psionics let's you also use BB against packs of armored elites to great effect, killing or otherwise staggering them. On ult use, BB charges VERY fast and doesn't generate peril.  Amazing for elites and also bosses!
• Cooldown reduction from Psykinetic Aura and Seer's Presence (plus any cooldown reduction curio perks) let's you maintain a lot of uptime on Scrier's gaze. Scrier's gaze longevity is enhanced by Battle Meditation.
• Stacks multiple sources of toughness damage reduction and toughness regen.  One with the Warp and Endurance gives solid toughness damage reduction.  Couple this with fast toughness regen from perk curios, plus you have Quietude, Soul Stealer (amazing with special force sword attack), Mettle, and Psychic leaching that all keep your toughness topped off. Kinetic deflection helps in a pinch, especially outside of Scrier's Gaze to keep peril high.
• Crit synergies aplenty:  Gain bonus crit from Headhunter (on ranged), Bloodthirsty (on melee), Scrier's Gaze (+20%), and True Aim.  Landing a crit boosts toughness regen & movement speed (Mettle), dodging ranged attacks (Empathic Evasion).  Plus you can set enemies on fire with Inferno (on ranged).

There are a few talent picks for fun.  Kinetic Flayer is unreliable but a lot of fun when it pops off and kills a crusher or other elite instantly. Perilous Combustion isn't a huge damage dealer, but it can work well when clumps of elites are bunched up and you rapidly BB them down.

Alternative talent considerations:

• Instead of Seer's Presence, can run Prescience for an additional +5% crit chance across the board.  Since you won't be able to access One with the Warp, can swap to Anticipation (stronger dodges) or add Warp Speed for even more movement speed. This option grants even more crit potential, but extends the Scrier's Gaze cooldown.

Curio Selection:

• Psyker benefits tremendously from one +3 Stamina Curio. They have less stamina normally and run a bit slower, so the extra stamina really helps your mobility, ability to push in melee, and blocking capacity.  
• Other curio blessings should be +Health to keep you going longer.  Psyker has a smaller amount of toughness, so it's more important for them to keep toughness topped up at 100% to protect against chip damage in melee - but when your toughness does break, having more health is better. 

Melee Weapon

Illis Force Sword works the best with this build, letting you carve through hordes.  The special attack counts as a warp attack and synergizes with soul stealer to regain a ton of toughness while in melee and keeping it topped off. Shred gives a huge increase to damage output with chained hits and crits. The Force Push (push attack) on the force sword is great to make space against armored elites.  Slaughter is the best all-purpose damage magifier for the sword.

Alternative melee weapon considerations:

• Exorcist Blessing (instead of Slaughterer) can extend uptime of Scrier's gaze in melee, but you need to land chained headshots, so can be trickier to leverage to the fullest.
• Can give up either of the blessings for Deflector if you find yourself getting caught in the open too often. Deflector is still amazing for survivability on psyker.
• Deimos force sword is a solid alternative and gives you a great tool for 1-hitting crushers.  Run it with Uncanny Strike for amazing rending damage. 

Use a force sword on this build, because you can mix in quick quells during melee combat when Scrier's Gaze pushes your peril towards 100% in order to maintain up-time on Scrier's gaze.

Ranged Weapon

MkVIIa Recon Lasgun with Infernus and Headhunter synergizes well with all the other crit bonuses on the build, dealing solid damage and also lighting enemies on fire.  In lieu of Headunter, can also run Stripped Down or Hit & Run for extra ranged defense. Dumdum stacks up to 5-times and triggers from fire stacks/ticks so can be a solid damage multiplier and option..

Alternative ranged weapon considerations:

• Laspistol with Infernus for a similar effect
• Columnus Mark V Infantry Autogun if bullets are more your thing - although it loses some of the advantages that the crit-centric build brings.
• Zarona Revolver can also be used with Surgical + Handcannon, but it ends up being somewhat redundant with your BB ability.