PsyEmperor
 Psyker Build - Warhammer 40k: Darktide 

The perfect tough yet brainless zap pew build for Psyker

Duelling Sword (or Illisi force sword)

Perks:

• Maniac - Lets you one shot heavy Mutants without Warp Rider 
• Insert for most hated group here - Elites, Crit chance, Carapace, Flak, Unyielding any of the above is fine

Blessings

• Riposte - This weapon has some of the best crit multipliers in the game making crit chance actually good
• Uncanny - Rending is incredibly strong post patch 13

Surge - Perfect for long range single target removal, charges incredibly fast and quickly fills our peril gauge.

• Flak - For one shot charged shot kills on shotgunners, and one shot crit kills on scab gunners (at high peril) 
• Maniac - one shot crit flamers and one shot trappers. 
• Crit chance is a fine alternative for either as the base crit chance for the weapon, and class is huge, making it very consistent damage increase.

Blessings:

• Warp Nexus - Way more consistent criticals, for more consistent damage - we are always going to have easy high peril on this build.
• Warp Flurry - Faster shots and you 2 shot just about everything in the game. 

Use Venting Shriek to clear out hordes with Creeping Flames, and Perilous Combustion a single tap will clear out everything you are looking at. With full Warp stacks the cooldown is incredibly low letting you easily do this every horde, often multiple times a horde.

WildFire - Sounds like you would want it, but you don't. Because it has a max of 4 stacks it can't even refresh enemies soulblaze stacks if they are higher. 4 stacks won't even kill Groaners at full life, meaning this skill provides very little.

Use Smite to lock down hordes of Mutants, Pox hounds/Bursters  or Elite/Crusher spams in Auric Maelstrom. It is also a great tool for building Peril to so you can burn everything with your ult. It also increases the damage enemies take from SoulBlaze. Empowered Psyonics is not critical for Smite but the 50% faster spread is strong (damage on smite is roughly 65 DPS, so even with 125% increase is it still awful.) so we will just stop at Over Powered Souls. 
Make sure to hit Venting shriek after Peril 85%, but before you are forced to stop Channeling Smite as that will force you to recharge, and respread the lightning. Also Enfeeble will increase SoulBurn damage so it is good to have that going while they burn.

Lightning Storm (And Smite rundown) - appears to increase the range by 1m, from 15m, to 16m for the first 1-3 targets (Right click will pretty much instantly start with 3 initial lightning bolts. Left click starts with one and can build up to 3 when channeled long enough and if you mouse over a target not currently affected by Smite) bounce range from 5m to 6m (all targets after the first 2/3) and total targets by 1? (I am uncertain there is a unit limit so long as enemies are within bounce range, mostly restricted by the time it takes to spread across units - doesn't impact the number of initial targets) The bounce range is the only thing of limited value, overall I don't recommend this talent.

Enfeeble - only works on uncharges (left click) smite, not too critical to take since you normally want to charge for faster spreading

Also Smite will knockback/knockdown all enemies currently being hit, if you MANUALLY stop casting it. Doesn't really impact Ogryn or ragers. 

Warp Siphon is a fine alternative but you will lose all stack everytime you ult (and you will do that very often) and requires more talent points to be effective.

Remember SoulBlaze kills and Staff will give you 7.5% toughness per kill, and can very rapidly regenerate toughness. Quietude + Battle Meditation + Venting will also quickly refill your toughness bar when used together. and again we will be doing this combo a LOT.

Crit chance boost can be swapped for more TDR if you want a little more survivability instead of damage.