Voidblast Psyker (Jeficus)
 Psyker Build - Warhammer 40k: Darktide 

This is my favorite variation of the Trauma Staff Psyker build. It's great at doing uncapped AoE damage and crowd control to nearly every enemy type.

Pros: Great AoE DPS, Special Sniping, Crowd Control, doesn't use ammo.

Cons: Survivability in certain scenarios, lower single target damage than a boss killing build.

Weapons

In this build you want to use the Mk III Combat Blade or Mk IV dueling sword because they are your highest single target damage options.

Your ranged weapon is going to be the Mk III Trauma Force Staff which is going to deal most of your damage as it does uncapped AoE damage to all enemies hit within its radius. I recommend taking Flak damage and Crit chance for your perks and Blazing Spirit and Warp Nexus for your blessings to maximize AoE damage.

Curios

For Curios I run a one stamina curio and 2 toughness curios because Psykers can really struggle with damage mitigation due to low maximum stamina and toughness, but they have plenty of toughness regeneration through your talents (which is % based, do not rely on coherency toughness regeneration). Grab Ability Cooldown, Stamina Regeneration, and Extra Toughness, Sprint Efficiency, and Block Efficiency. You're going to be using your ability whenever it's up so you really want as much cooldown reduction as you can get and stacking stamina benefits makes surviving much easier.

Talents

Every talent you take at the top of the tree improves your survivability by allowing you to regenerate toughness by killing enemies with warp attacks, generating peril, and quelling peril. You don't take Warp Expenditure because of the way the talent is balanced, you're never generating enough peril to make it worth it.

Don't take any of Brain Rupture's Blitz Modifiers because you will only be using it to kill Gunners and Snipers that are too far away for your team to handle. Your highest single target DPS will come from your melee weapon.

Our primary sources of damage increases outside of our keystone will come from Perfect Timing and Warp Rider, which just award more damage for doing the things we are already going to be doing.

Psykinetic's Aura and Seer's Presence are must takes because they provide valuable cooldown reduction to the team whenever any of you kill special and elite enemies. This allows you to spam all of your abilities, increasing all of your damage and survivability.

For Venting Shriek you'll take Creeping Flames because 6 stacks of Soulblaze is enough to kill all basic enemy types in the game (including shooters).

Lastly you want to take Warp Siphon and as many of its modifiers as possible because of its powerful synergy with Venting Shriek. You will be getting a ton of kills with this build in Auric Maelstrom because when you pop Venting Shriek into a horde of enemies everything will have Soulblaze.