Scriers Voidstrike
 Psyker Build - Warhammer 40k: Darktide 

The idea:
Use the Warp Unbound sub-node of Scrier's Gaze to push Voidstrike to its limits without quelling.

This is by no means optimal. You can absolutely get equivalent or better results in a standard Voidstrike build that isn't constantly playing so close to the wire's edge. With that said, I still find it to be a lot of fun. The entire crux of this build is Warp Unbound. For 10 seconds after hitting max peril, you must go buck wild spamming your Voidstrike. Because of the peril generated by the staff, Scrier's Gaze rarely stacks very high, so we're missing out on some potential damage outside of any scenario where you get to bowl charged shots through a densely packed, tight corridor. Activating Scrier's Gaze still provides an instant 20% crit chance and damage buff, which is valuable for triggering the Surge blessing for regularly one-tapping hard targets as well as for spamming machine-gun primary fire. When able, remember to debuff high-health targets like Crushers and Monstrosities with primary fire for the 30% warp damage from Empyric Shock.

The risky nature of this build and the cost of playing without Telekine Shield makes it pretty non-viable for high-level Havocs. Still, it is admittedly fun for Aurics.

Melee choice is irrelevant to me. I prefer mobile weapons like Combat Knife or Dueling Saber, but one of this build's weaknesses is horde management so your choice in melee can make up for that somewhat. If you can get by with a Devil's Claw, more power to you. One positive of running Scrier's Gaze/Disrupt Destiny is that the damage/finesse boosts will make your melee less of a wet rag, but in my preferred configuration, we're opting out of some of the talent nodes that actually buffs melee specifically like Lightning Speed's 10% melee attack speed.

Blitz choice is also mostly irrelevant to me as we won't really be using it unless we have to. Smite is a flex choice to make sure we get Psykinetic's Aura, which is crucial for having high uptime on Scrier's Gaze. Executed properly by focusing on elites and specials, you will have very short cooldowns on Scrier's Gaze because of Psykinetic's Aura. Sniping priority targets is thoroughly covered by the Voidstrike Staff. Smite is, thus, the most useful choice between Brain Rupture, as it has utility for panic moments like securing a revive or giving teammates a moment to breathe. In my configuration, I do not take the Lightning Storm sub-node which can hamper the total effectiveness of Smite's stun.

Considerations:
Perilous Combustion might be superfluous enough to the build that you could throw that talent point in a number of other nodes. Grabbing the aforementioned melee-centric node Lightning Speed, for instance. Other safe choices could include doubling down on toughness passives like Soulstealer or Warp Expenditure at the top of the tree, or the Endurance sub-node of Scrier's Gaze for toughness damage reduction. If you like Smiting, taking at least Lightning Storm will enable you to lock more targets down. I don't recommend using Smite for horde clear with Enfeeble without fully investing into Empowered Psionics-- the damage is just too low. You would be better off just activating Scrier's Gaze and switching to melee in most cases.

The two point dive to pick up Empyric Shock is the only other flexible point of this build, in my opinion. The damage buff of Empyric Shock doesn't have consistent uptime, granted, but I find it useful still. With those two points, you could go for One with the Warp instead for extra toughness damage reduction, which will have a guaranteed high uptime given the nature of this build. For the purposes of my configuration, I prefer to go full glass canon. I advise against taking the two point dive for Penetration of the Soul for 10% rending. If this node even works, 10% rending is an almost entirely negligible amount of penetration despite having a theoretically consistent uptime.

Of special consideration: Crystalline Will. I don't know if I should need to comment on this. This build is playing with fire. It is purposefully drawing power from sticking a fork in an power outlet. Typically, I avoid Crystalline Will as in the most ideal scenario you will have your peril management locked down without it. That said, accidents happen. In testing this build, I lost track of my Warp Unbound buff at least a couple times over several runs. More than any other Psyker build, this is the one that I felt most inclined to run Crystalline Will, but even with that said, I still prefer to go without it.

It's important to note that the idea is to stay at 100% peril while in the Warp Unbound safety net, so sources of passive quelling are anathema to the build. Battle Meditation, Purloin Providence, and even Empyric Resolve are useful sustain to try to get higher stacks of Scrier's Gaze (similarly taking Reality Anchor over Precognition subnode of Scrier's Gaze), but that's not inherently our goal.

Considering the Voidstrike Staff: the top picks for perks are Unyielding, Carapace and Crit Chance. 10% Elite Damage in addition to Carapace is untested but worth investigating, though might be overkill. Surge is mandatory. We're going for as much crit as possible so Void Nexus has high value, especially since we're regularly planting ourselves at 100% peril and just going for it. One extra consideration here is to go Warp Flurry instead of Void Nexus to get out as many charged shots as possible during the 10 second window of Warp Unbound, but this is a pretty big trade-off in crit chance, especially without the 20% you'd be missing with Scrier's Gaze on cooldown. With Surge, decent Disrupt Destiny stacks, and the modest damage boost from Scrier's Gaze, a crit headshot should be capable of killing almost any elite outright. If a lesser elite survives due missing the headshot or crit, it's often easier to finish them off with primary fire spam. In fact, for most stray lesser elites, specials (other than Poxhounds) and close-range Reapers, it's faster to just use primary fire.