Staff Bolt Scrier
 Psyker Build - Warhammer 40k: Darktide 

This build specializes in spamming staff bolts (i.e. staff primary attack) with high crit rate to scale both direct damage and the extra projectile proc from Surge blessing. Crit chance on the staff exceeds 90% when all buffs are active and peril is maxed, and is around 50% with no buffs and low peril. Landing weakspots hits will significantly increase DPS against most targets, except against maulers and plasma gunners who have carapace helmets and flak body armor. Staff secondary attack can be used to open bulwark shields and damage crushers from range.

I chose the Mk VI knife for its high mobility and DPS against crushers and bosses. Other good melee options include the force greatsword, Illisi or Deimos force sword, duelling sword, or Devil's Claw sword.

Curios are mostly personal preference. I usually take 3x stamina regen perks on my curios, but since this build is primarily ranged I opted for health perks instead. You could drop the +3 stamina curio for another +17% toughness if you want, but I think having extra stamina is useful even on a ranged build. You could also swap out health perks for revive speed or whatever you want.

Smite is the recommended blitz because Brain Rupture and Assail are mostly redundant with other parts of the build and we don't have spare points for the upgrade nodes, but you can use whichever you prefer.

I recommend Prescience aura over Seer's Presence because crit chance is a massive damage multiplier for this build and Scrier's Gaze already has a short cooldown. Seer's Presence is generally more valuable to teammates though, so feel free to use Seer's Presence instead.

You can take Channeled Force instead of Souldrinker if you prefer, but personally I think the gameplay is smoother just spamming staff bolts instead of having to full-charge a secondary attack every 5 seconds for the CF buff. Souldrinker will also proc from killing any enemy that has soulblaze on them, which will be fairly common from Perilous Combustion or with another Psyker player on the team.

Just a Dream can be swapped for Lingering Influence if you want to sacrifice some defense for higher average damage.

If you don't like the reduced toughness recovery on Empyric Resolve, you can swap that out for something else. You will likely have less Scrier's Gaze uptime without Empyric Resolve though.