berpsyker
 Psyker Build - Warhammer 40k: Darktide 

he final point can go on Souldrinker (if you're playing with an Inferno Psyker or other source of soul blaze), Warp Speed (my personal preference, though I know its not liked by some, or True Aim (recommended for general use, like quickplays)

Reconlas can also be substituted for a Vraks Infantry Autogun, with Flak and Unyielding damage, with Raking Fire and DumDum as the blessings. Ammo as the dump stat is my preference, but mobility is also a viable dump stat. 

I also sub out the minor +5% hp nodes on the curio for revive speed, and drop one ability CDR for a grimoire resist, but this is due to preference and is not recommended either.

HOW TO USE: (TLDR at bottom) 
You will mainly be using the FGS (melee) for this build. you will use light attacks for horde clear, and heavy attacks for single target. if you want a more technical approach, light attacks 1, 2, and 3 are sweeping attacks, and after any of these attacks, perform a block cancel by holding block for just a moment before continuing your attacks to loop this pattern. this will allow you to bypass light attack 4, which is a strikedown single target attack. heavy attack 1 is a strikedown, and heavy attack 2 is a very strong stab attack, perfect for dealing with crushers in a swift manner, as well as maulers, ragers, and other bothersome heretics. to access heavy 2 in a quickly, perform light attack 1 then initiate the heavy attack, which will be this stab attack. an alternate horde clear pattern is to loop the following pattern: light, light, light, heavy.

if you are using a recon lasgun, will mainly be used to get crits to then proc empathic evasion, which will make you immune to ranged attacks during its 1s duration. reconlas' fast firerate and high ammo capacity allows for reliable safety when dealing with gunner lines and reaper clusters.

if you are using a vraks, this is less reliable, as aiming is harder and the firerate is slower, as well as the ammo capacity being lower, however it does pack more punch per bullet, so it will do the following job very well.

your gun will also be used to take out monstrosities, ranged enemies, and specials. otherwise, you will be focusing on hitting the closest things with your sword. the sword is also a viable option for fighting monstrosities, though this depends on how well you know their attack patterns, when to dodge, etc.

assail will be used to also deal with specials, elites, and to assist with horde clear, mainly to proc Malefic Momentum, which will greatly increase your damage with both the assail, and your melee/ranged weapon. you will try to weave assail with your sword attacks, i generally throw two then go back to melee. assail will also stagger ragers, so if a swarm of them comes after you, throw a few to let yourself reposition and get some attacks in while they recover.

ideally you will maintain around 80% peril, to get the most out of all the peril-reliant talents, while still allowing you to throw an assail or FGS special attack. However, if you are newer to the peril edging mechanics, you can start out around 60% to still get decent benefits, then slowly increase the threshold you edge at until 80%.
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TLDR: sword 90% the time, lights for horde, heavies for single target. assail for horde clear assist, blue man killing, and building peril. gun for crits for ranged attack immunity and specials/elites too far away to bonk.