Itty Bitty Critty Needles
 Psyker Build - Warhammer 40k: Darktide 

High Crit Chance build. In order to get the maximum effect from Disrupt Destiny keystone we use needles to pick out the highlighted target as we move and fight. This allows us to run at high crit and weak spot damage all the time. True Aim gives us guaranteed crits since needles frequently hit weak spots. Use Scrier's Gaze ability to deal with large groups. It instantly quell's 50% peril and gives you more crit chance and weakspot damage. I also take Precognition because we love finesse damage. We like to maintain high peril with Just a Dream because we get bonuses in damage (Warp Rider), cleave (Warp Splitting), toughness damage reduction (One with the Warp) and toughness regen (Quietude). This also works well with Scrier's Gaze as we are constantly running up high peril, just be careful about hitting max and ending the bonuses. We take Warp Unbound to give us a little safety net from ourselves and Mind in Motion to protect us while we manage our peril.

Pretty much all the other perks give us bonuses from crits or enhance our crit chance building ability.

Mettle -Toughness,movement speed buff from crits

Perfect Timing - Damage buff from crits

Prescience (aura) - Crit chance

Empathic Evasion - Evasion on crit

Anticipation - Better dodge, synchronizes with Riposte and Precognition on the sword

Psykinetic's Aura  - Cooldown reduction on elite/special kill means you get Scrier's Gaze more often

The sword is pretty perfect for the build. I also like the voidstrike staff because its penetration stacks very well with the rest of the perks, but adding extra damage against certain enemy types might work better for you. Curios are  mostly up to preference. 

At Heresy level the needles become much less effective and it is harder to maintain the benefits from Disrupt Destiny which makes the build start losing utility.