crit popping scrier
 Psyker Build - Warhammer 40k: Darktide 

Your role in the squad is the guy with the bazooka.   Charged voidstrike heavies will be your goto and these are very strong at dropping high priority tough targets and clearing corridors or dense packs.  A lot of this strength is down to the staff setup which offers high crit chance and very high crit damage all on its own.

The build leans into criticals with 'scriers gaze'  (+20% crit) -> which puts your critical chance between 48 (0 peril) and  63 (100 peril) 

Thats pretty much all there is to it -> you can deliver massive damage to any spot you can see from any range with only the above.  Everything else about the build is help the player to get that happening safely and reliably as often as possible.

Playing the bazooka guy is a back line role, so often you wont be in coherency.  Front liners tend to be highly mobile while attacking and they move forward at speed, while you have to plant your feet to attack, which results often in being isolated and playing catchup.  There is also a certain tunnel vision that can happen where you are charging your next shot and scanning the field of view for the best place to put it, and the temptation to just stick in one place and keep deleting absolutely everything you can see is very strong.  

but thats how you get killed by something hitting you from offscreen.  Because often you CAN just solo clear everything from a good vantage point.  But often you get ambushed while trying to do that.   Also, if you are clearing entire engagements,  it gets kind of annoying for your frontline teams mates as blue explosions rain down and when the smoke clears there is nothing in front of them, so they rush to the next location to find some action, leaving you far behind and isolated.

The key is to continually stick and move, prioritizing dangerous threats with a shot or two, but then immediately relocate to another position and let your teammates mop up.  This keeps them occupied while you reposition  and allows you to stay safer from being backstabbed.  Dont kill everything, kill 1-3 dangerous priority targets (elites and specialists mostly) and then move.

With this in mind, mobility is KEY, hence the sprint efficiency on the curios (+60% stamina for sprinting effectively).  Also mettle, mind in motion and warp speed.  quelling while repositioning at speed  in sciers gaze is efficient use of your time.

Of course when the shit does hit the fan you need to resort to your sword and start severing heads with chained wide sweeping blows.  the criticals will stack up -> mettle and 'by crack of bone' will both kick in, allowing you to stay in scriers gaze for quite a while.  crack of bone isnt great, but its a mandatory node after mind in motion and it does remove enough peril to keep  scriers gaze active while lopping heads

The two big questions are blitz and keystone.  

brain rupture -> Kinetic flayer is the thing you want.  You will rarely manually pop a head unless it is an EXTREME range dangerous target and nothing else is going on, or maybe a monstrosity.

kinetic flayer activates on specials and elites and so does warp siphon.  At the start of a skirmish its nice to just one tap touch the 1st HP target you see and get a warp charge.  And every 12 seconds after that, a HP targets will die a lot easier.  Even if you just clip an elite with area damage, the brain burst will likely take them out.  it makes taking out high speed or long range targets a lot easier.

Assail requires manual switching to compete with a role your staff is already doing a better job of, while kinetic flayer compliments it without you having to think about it.  There might be a case for smite as a defensive measure to pull out when youre in trouble, but that locks you in place again, when often the best thing you can do with this build is to hotfoot it to a better position before things get out of hand.

warp siphon: TBH I cant tell if its better than disrupt destiny for this build in a straight up comparison -> its more about the nodes you pick on the way.  Personally I try not to pick nodes that require headshots because from my couch with a controller, Im just not skilled enough to make good use of them for me, most ranged headshots are accidental.  Also, hunting marked targets competes with identifying high priority targets, so definitely a combined skill bar that is too high for me.  Otherwise true aim would be great and movement speed would be welcome on the way to disrupt destiny absolutely deleting things with high skill play.  Your call.

Personally, I like much reduced peril generation and quicker quelling, allowing you to stay in the '40-80 peril zone' (more crits, more damage) more easily and for longer, and increased uptime for scriers gaze.   All you have to do to maintain warp charges and sciers gaze is manage your peril, which is something you have to do anyway.   It allows my small brain to concentrate more fully on dangerous target identification and repositioning.