Super Psyker 3
 Psyker Build - Warhammer 40k: Darktide 

• Illisi sword should have 80% for Damage, Finesse, First Target, Mobility, and 60% for Warp Resistance. You don't want to be needing to empower it very often, but when you do, you are mostly using it to keep your peril high for Venting Shriek or Warp Rider. Focus entirely on spamming light attacks on enemy weak spots, especially if there are massed targets. Light attacks are more than enough to lay waste to everything in your path once you have killed 5 targets to gain 5 stacks of Slaughterer and struck 5 weak spots to gain 5 stacks of Uncanny Strike. Don't worry about empowering the blade or charging up heavy attacks most of the time, unless you're just swiping at a lone target and haven't yet racked up your Slaughterer/Uncanny stacks.
   
• Voidstrike staff should have 80% for Damage, Warp Resistance, Quell Speed, Blast Radius, and 60% for Charge Rate. You don't want to be needing to fully charge your secondary very often, but when you do, you are mostly using it to headshot Ogryns or other groups of armored enemies that are currently standing still and not shooting at you. I chose to eschew Warp Nexus in favor of Surge/Blazing Spirit so that every crit has two secondary effects, instead of just more crits with only one. Don't worry about the lack of Warp Nexus. Voidstrike gets LOTS of opportunities for weak spot hits due to the large size of the secondary attack's projectile, so it gets a lot of mileage out of True Aim. Just note that with Blazing Spirit, the stacks of soulblaze are not applied until the secondary projectile explodes. It will not explode unless it has struck terrain or a heavily armored target. This means firing from an elevated position is more optimal despite the fact that the projectile might hit fewer targets directly. This will take some practice, but you can also jump, aim at an enemy's head, and fire downwards. This ensures your blast will hit both a weak spot for True Aim and detonate on the floor for soulblaze application.
   
• Malefic Momentum is extremely powerful and should never be neglected. It gives +30% to warp damage after 5 non-warp kills (acquired via melee, in my case) and +30% to non-warp damage after 5 warp kills (which can come from either Soulblaze OR direct damage from Voidstrike) therefore you want to maximize how often you are switching between melee and ranged.
   
• Venting Shriek is useful for many things, from peril management to tactical knockbacks, but I primarily use it offensively to apply soulblaze to massed groups of enemies. If you can manage, wait until you have at least 80% peril, and are at 5 stacks of Malefic Momentum, Perfect Timing, Slaughterer, and Uncanny Strike. This means that the 6 stacks of soulblaze you apply will be at their absolute maximum damage potential from the moment they start ticking. But don't let this be a hard requirement. Use it whenever it feels like the situation calls for it, especially if you are at least at 80% peril. You can always shriek first and build up the buffs after; this will still be more than enough to melt entire swarms of any type of enemy.
   
• Smite is a defensive tool only in this build, it will not do significant damage even if you have full stacks of Malefic Momentum and Uncanny Strike, because Slaughterer stacks become inert the moment you un-equip your melee weapon, so unfortunately we cannot reach max power in a melee rush and then switch to Smite to freeze everything in place while it melts to dust. I primarily use it to lock enemies down while my teammates are trying to do something (mission objectives, revives, etc) or to lock down particularly annoying enemies like Poxbursters/Mutants/Hounds.
   
• Curio perks are mostly self-defensive, as I often blindly jump into whatever mission Auric Damnation Quickplay throws me into, and thus I cannot trust other players not to be already holding Grimoires, nor can I trust that we will have a Veteran keeping enemy gunners from becoming a problem. If I was in a pre-made group that I trusted not to grab Grims, and had a designated shooter-suppressor to handle gunners, I would probably swap the 20% anti-Grimoire for Combat Ability Cooldown, and the 20% anti-Gunner for something more globally useful like 5% Toughness.

My video demonstrating this build is a bit of a meme, but it's also an honest representation of the power of this build. It demonstrates that once you have stacks of soulblaze on a large quantity of targets, it doesn't matter how strong or heavily armored they are, just start spamming light attacks with Illisi to keep up Slaughterer/Uncanny, and the damage will be unbelievable.