Gun Psyker
 Psyker Build - Warhammer 40k: Darktide 

Resilience and versatility will be your tools to outlast the hordes of Chaos and bring them to heel.

Your Sword, shall be the slayer of hordes, bequeathing Soulblaze, and cutting them down where they stand. Imbue your blade with Warp Charge to deal with specials and elites without switching weapons if you so choose. While in melee with the hated foe, use your Psykinetic Wrath at will, to make room to maneuver or ignite the pestilent flesh before you. While in Cohesion, your allies will help give additional Warp Charges, keeping your Toughness high and igniting additional filth with Soulblaze. If the forces of Chaos divide you from your allies' fear not. For you still benefit from the chance at additional Warp Charges, generating Toughness to persevere against the unclean,and Soulblaze to purify your foes.

Your Revolver will be your best friend in the fight against tough or ranged foes. Aim true and lay low enemy soldiers. Penetrate the ranks of charging hordes. And annihilate most specials and elites in a bullet or two to the skull. Keep your chambers loaded at all times and don't be afraid to load a bullet or two when required in-between actions. You never know when you'll need them when your Peril is high.

Your psykic power to Brain Burst your foes should not be underestimated, but also not over relied on. Plague Ogryn and the like are highly susceptible to your Brain Burst. Use it to target special and elite enemies, when possible, causing theirs heads to become nothing more than paste. When required, target lesser foes, if you need to strength your Toughness. Above all, if you target enemies your allies are likely to kill, make sure your get over half a charge for the Warp Charge to be gained.

Your dexterity will allow you to swap between your sword, gun, and psykic powers quickly and efficiently allowing you to have the best efficient tool at hand: Use your Brain Burst to assail the minds of Ragers, Maulers, or the like. Equip your Revolver (Quickswap Twice) to cleanse the weaklings remaining. Rain Revolver fire down on the mobs and the watch as limbs fly and blood sprays. Swapping to your blade as the foe closes to melee, meeting your blade and burning for their impetuousness. Dodge back and equip your Revolver. Letting a shot ring out into the melee killing many in a line, as you target that malicious Bomber in the back and Burst his Brain.

Your choices and actions are yours alone Psyker. I pray you choose well with the tools provided and have many successes against the profane.

The Emperor Protects

Inquisitor Val'kyr, Ordo Hereticus

Note: I apparently didn't log in when I posted this and so the other post of this with “Anonymous” is my build without credit.