Challenge God with a Spicy Stick
 Psyker Build - Warhammer 40k: Darktide 

Void Cannon

This is a Equinox Mk IV Voidstrike Force Staff secondary attack build with enough melee oomph to REALLY bring the heat.

Sadly, Equinox Mk IV Voidstrike Force Staff fires too slowly to be viable for the average player in missions above damnation, and even damnation can be a struggle if your tammates don't make SOME effort to keep the heat off you.

Once the right damage talents are spooled up, even without kinetic flayer, you can oneshot a damnation Crusher with a headshot crit.  With Kinetic Flayer, you can oneshot a damnation Crusher with a non-crit headshot. 

Why not Equinox Mk III Voidblast Force Staff?

The voidblast staff has great CC, but it is a vertical column in a game that operates on a horizontal plane.  In addition, it is almost required to have solid teammates.  Firing the voidstrike staff through a horde with its seemingly infinite cleave, can get you DOZENS of kills per shot.  The first elite/specialist you hit get smoked by kinetic flayer.  And then keep going.  You can aim for the crushers and get the maniacs running in front of them. 

Kinetic Flayer, on reading the description, doesn't seem that amazing.  A 12 second cooldown?  That's an eternity.  It is ABSOLUTELY a god-tier ability.  It regenerates fast enough that in larger waves, it can save you in critical moments multiple times.   When travelling from one engagement from another, you can oneshot any mutant that charges with a single primary attack.  When you are hacking away with melee, you spend enough time to reset the cooldown.  Then you swap to the staff, with Malefic Momentum active, and you can oneshot the biggest threat, then switch back to melee, use warp slice, and severely damage or kill any maniacs, ragers, weak specialists, and all the small enemies.  This attack combo can cut an entire wave down to 10-20% of its strength if it isn't too spread out.   

Talent swaps - At low difficulty ranks, you can swap Anticipation to One with the Warp.

If you are skilled, you can drop Mettle (Top right of the tree) for Warp Rider (Top right perk of the middle keystone tree)

Staff Blessing Swaps

A swap that is necessary at higher rank or by preference is to take Warp Flurry.  The increased fire rate is VERY important for the vastly increased number of enemies you can stun.

Melee Weapon Blessings.

Deflector or is an incredible blessing for when a ranged captain is focusing you or a gunner targets you.  It is great for survivability.

You could trade this out if you don't need or use it.

Melee

The Covenant Mk VI Blaze Force Greatsword is a beast of a weapon.  It has exceptional range, a great sweeping light attack for horde clear, downward heavy attacks that do excellent damage, and most importantly, has a ridiculous special.  

The special charges on kills and has two tiers of attack power.  It takes 10 kills to charge to the first tier, which can oneshot Maniacs and Ragers at close range with Warp Slice active.  

At full charge it does 3500 damage point blank to a crusher without warp slice.

As long as the elites are close to you, the wave will do full damage to them.  The damage will lower the farther away it gets, but will still wreak hell on hordes.  Specialists and elites count as 2 kills for the special.  This means it charges in 5 kills for the lower power attack and 10 kills in the higher power attack.

Melee weapon alternates.

Deimos Mk IV Blaze Force Sword does not have the horde decimation of the Covenant Mk VI Blaze Force Greatsword, but it does have 1 thing in spades.

Agility.  The dodge distance, speed, and number that the Deimos Mk IV Blaze Force Sword has makes it MUCH easier to use in higher level content.

It has a strong single target special attack that can be deployed quickly and target weakspots for good damage.  It is closer to the dueling sword in use than the Covenant Mk VI Blaze Force Greatsword.  I like it just as much as the Greatsword.

Maccabian Mk IV Duelling Sword , as it is not yet nerfed, provides not just unsurpassed damage and crusher-stagger, but AMAZING mobility.

Thrust and Uncanny Strike blessings.  Carapace damage and Flak damage perks.

Parry is an insane special ability.  You can parry every attack in a demon host's brutal attack rush.  Not only that, but parry's retaliation strike does great damage.  You can parry spam any boss besides the Nurgle Beast to death.  Whilst crushers take low damage from the devil claw, kinetic flayer does pop up pretty often.  

Aura

At higher rank, Kinetic Presence should be swapped to Seer's Presence.  Boosting your team's cooldowns by 2.5 curios worth of ability regen is EXTREMELY powerful, and I almost always run it.  It is an INCREDIBLY POTENT boost for any shout veteran on your team.  If they have a good build, your build can make them get their shout back in eight or so seconds after the effect ends.

Note:  I do not know if Malefic Momentum works on Covenant Mk VI Blaze Force Greatsword's special attack, but if it does, that brings Malefic Momentum to an absolutely necessary pick.  That it might synergize further with Warp Slice  just makes the choice more important.  

General note:  I see a lot of people fail at pushing pox bursters.  You need enough stamina (people claim it is 2 stamina) to push a burster far enough.  Having 1 or 2 stamina regen boosters on your curio can and will help you maintain enough stamina to push properly.  Also, don't sprint before pushing the burster.

Final thoughts.

The more skilled you are at Darktide, the less damage you take.  This means that the highest level builds are almost all much more delicate than builds for the average player.  This build is a very solid starter for a newer psyker and will take them up to Auric.  As your skill level grows, you can ditch early talent points for toughness regen and reinvest them elsewhere for more damage or utility.