The 'Good' Smyker Build
 Psyker Build - Warhammer 40k: Darktide 

Disclaimer:
This is NOT an easy build to master despite its simplicity nor people will praise You for using it usually... but every hater/uneducated fella shuts up when the build performs well XD (unless They are petty and keep yapping; let them - its free entertainment XD)
TIPS:
1. At the very beginning of the match when You reach first enemies target Elites with Your Ranged weapon in order to gain 'Empowered Psionics' stack if possible
List of Elites ranked for You to kill in order to gain a stack fast;
Shotgunners > Gunners > Ragers > Plasma Gunners > Maulers > Reapers
You should not try to kill Bulwarks or Crushers; they take too much time due to high HP and Carapace on a Crusher
2. Your Ranged option should NOT be a staff for 2 simple reasons;
- Using Smite will alot of the time leave You at high peril at which when You have to pull out Your range in order to deal with a Special You will not be able to due to it
- Why would You ever use Your staff when You have Smite to begin with?
A) Purgatus offers better damage but no CC; especially againts Bulwarks and Crushers and in situations where You will have no space to maneuver in. Smite will save You and Your team; Purgatus won't
B) Voidblast (aka Trauma) offers good CC, reasonable damage and nice debuff potential through Rending Shockwave blessing but in a wide area it will lose potency especially if Your team is scattered. It is also important to note that once it staggers Bulwarks and Crushers Smite will not affect them for approximately 3 seconds
C) Voidstrike is nice againts funneled enemies and is the best of all staffs to deal with distant threats like snipers but due to how it works it offers barely any CC. Great choice if You use Smite but not in this build
D) Electrokinetic is nice againts scattered enemies and single targets outside of bosses but its worthless when dealing with big crowds. Great choice if You use Smite but not in this build
The best choice is a quick responce, single shot weapon that can be used at long range with ease
List of Range weapons from Best to Worst;
A) Bolt Pistol (checks everything You need; minor Boss damage due to Puncture, good stagger, good mobility and the ability to restore Your toughness due to Gloryhunter which also procs from Puncture)
B) Zarona Revolver (Has good stagger, mobility and damage but can be easily suppressed and the reload can be a pain at times; has the ability to restore Your toughness due to Gloryhunter)
C) Heavy Laspistols (their only weakness is that they don't stagger that well nor kill as fast as a Zarona Revolver or Bolt Pistol; other than that good choice all around with an access to burn DoT)
D) Agripinaa and Accatran Combat Shotgun (falloff damage is acceptable especially if You will be using Agripinaa; Accatran has burn DoT utility and better suppresion)
E) Agripinaa Revolver (not great at long range but it will do nice damage againts Unyielding; its also very reactive)
The rest should NOT be used with this build!
3. Your Melee option is just 1 really and its a technical choice; Mk IV Force Sword due to Deflector and acceptable single target damage. Perk choice is important aswell;
- 2 stamina because of low base stamina on the weapon itself (2); its there to boost Your Deflector, sprint and block efficiency on top of being able to push more (thats why 20% block efficiency is not better than 2 stamina)
- 25% Maniac damage because You can 2 tap a mutant in H40 by using 2 powered up heavy attacks at 0 peril; they do exacly +3k damage and Mutant has 6k HP on H40. It also helps againts Flamers and Trappers if they happen to end up in Your melee range
You could use Force Greatsword but its way slower than the single handed variant and its powerup is a horde clearing one that needs kills to be effective and thus it should be avoided
4. Gameplay is simple; You Smite, You shoot and melee from time to time, You win BUT it has some caveats to it;
A) Watch Your positioning; its the key to victory on every class really but on smyker its crucial. Watch the terrain You fight on - know where to retreat when You have to and where to take cover if You get focused at range
B) Do not use your melee unless its absolutely necessary; its for blocking againts ranged units and Bosses that focus You and for killing Specials that get too close, especially Mutants
C) Do not engage Bosses; You are NOT a Boss killer by any capacity - Your main role is to stop everything that comes with the Boss so that Your team can focus it in peace. At the very best You smite them by proxy to apply 10% damage debuff from Enfeeble on them and shoot 4 times with the Bolt Pistol in order to apply 16 bleed stacks if you use it; same goes for 12 burn stacks if You're gonna use Las Pistols or 10 burn stacks if You're gonna use Accatran Combat Shotgun or magdump with Agripinaa Revolver. If it is a Captain - You melee it to break the shield faster; after it breaks use a powered up attack. If You know a boss is coming towards Your team try to avoid being at the front and damaging it first; this will draw aggro of it to You and its the last thing You wanna achieve with this build (there is an exeption; drawing Beast of Nurgles attention so Your team can hit its 'pimple' in the back to kill it faster)
5. This build has only 3 weaknesses and as I list them I will explain how to deal with them the best way You can;
A) Bosses - In order from Worst to Easiest;
- Sword Twin; The worst of the worst; once She focuses You its game over; You're useless until Your team takes aggro away from You. Arguably the only boss You cannot really engage in any way due to how severly She punishes You once She comes after You. You can do the same strategy as if You're fighting a Sword Captain (more below) but with way shorter window timing for punishment; 360 swipe attacks do not have the same opening and its very risky to engage while it is charged so it should be avoided
- Chaos Spawn; Extremelly dangerous once it focuses You. The only attacks that can be reliably dodged without You interrupting Your Smite is the 2 hit slam with both arms, grab attack and the 1 hit slam similar to the one Plague Ogryn uses while at point blank range; everything else is a multihit that drains Your dodges and forces You into blocking. Best way is to allow Your team to take aggro off You by any means necessary
- Sword Captain; Apart from obvious immediate toughness strip from a Plasma shot and to a degree from a shotgun his relentlessness is his main threat once he focuses You in melee. Way worse than the Crusher variant, his flurry of attacks will lock You into blocking and dodging while the shoulder charge, kick and shield burst will interrupt Your Smite if they connect. Wait for his combo to finish and then sneak in 1 - 2 hits at best in order to not get punished; his 360 degree charged swipe takes solid 3 seconds to execute and its perfect for You to either create distance or burst the shield down
- Crusher Captain; Apart from obvious immediate toughness strip from a Plasma shot and to a degree from a Shotgun his relentlessness is his main threat once he focuses You in melee. Less threatening than the Sword variant but still can easily interrupt You with shoulder charge, kick and shield burst. Relatively safe to engage in melee in order to burst his shield down and give You enough time to create distance
- Plasma Twin; Apart from obvious immediate toughness strip from a Plasma shot his mines can CC You and prevent escape if left unchecked. Try defusing them as they are thrown by stepping into the radius and then retreating (be mindful that they take solid 3 seconds after being thrown before they are armed; they will not detonate in that time so You can utilize that to run away from a disadvantegious spot). Stay in cover if You are focused; melee engage can be done but only if there is nothing else left to kill/CC with Smite and with caution due to obvious Plasma shots and sudden melee kicks
- Plague Ogryn; generally slow but has some attacks that can be dangerous to You; 3 hit combo and a charge headbutt are most noticeable. The rest can be dodged with ease without interruption of You smiting with correct timing (even the stomp)
- Beast of Nurgle; it is too slow and has only 1 attack when its focusing You which is the puke and grab when You get slagged. Very easy and should not give You any trouble unless in tight spaces with no escape
B) Ranged Units outside of range of your Smite and enemies not affected by it due to target limit - Due to how Smite works it sometimes does not affect certains enemies due to links being fully occupied which You can either break by moving Your camera away from smited enemies (which takes time to work and many times You won't have time, not recommended), stopping the Smite and reapplying it (not desirable but all depends on the situation You're in) or using Your ability to stagger them before they try to harm You. If ranged enemies target You while You use Smite and You cannot reach them in time seek cover in order to deal with closer threats and regain any lost toughness; after that engage from there by rapidly closing distance to them and smiting them. If thats not possible; use Your range weapon - Gloryhunter blessing will help tremendously with survival againts Gunners, Plasma Gunners, Reapers and Shotgunners
C) Stun Immunity - Most notable are Final Toll (aka Red Buff), Nurgles Blessing (only present in Maelstrom), Stun Immunity after staggering enemies such as Crushers, Bulwarks, Reapers, Maulers and Ragers, Red Stimm buff and Green Stimm buff while its in effect. All You can do is to pay attention to enemy animations/buffs and be alert at all times so that suddenly You don't get interrupted or worse; die
D) Being Surrounded/having many angles where enemies come at You - Always try to funnel enemies! Position Yourself so You can easily maneuver between most contested areas and apply Smite without the need to turn 180 degrees. If You get surrounded; back away as much as You can and funnel as best You can in order to stabilize the situation - use everything at your disposal (Your ability, pushing, abusing terrain advantage)
6. Venting Shriek should be used in the following situations;
- When You reach +50% peril in order to vent and +85% so You can apply 6 stacks of Soulblaze due to Creeping Flames augment
- When You or Your team end up in a tough situation where the stagger and the push it provides may be able to save lives or even games like pushing off a Pox Hound off a teammate who is behind a wall or a Poxburster which is not affected by Smite for example (yes this ability does overpenetrate hard surfaces!)
7. Other versions of Smite are not as effective as this one for various reasons;
A) Scriers Gaze is tempting for its way longer smite longevity and better damage but it loses stagger option with a press of a button which is Venting Shriek (not to mention some buffs like crit chance is wasted cause Smite can't crit (Thank The Emperor it can't XD)). It also loses synergy with other psykers present in the team which use Soulblaze
B) Telekine Shield is tempting for making range threats outside of Your reach nullified but it makes Your Smite very short lived and thus not as impactful
C) Warp Siphon Keystone is tempting for making abilities charge faster, reducing peril and giving nice toughness regen however despite even increasing damage its way worse in that field in comparrison to Empowered Psionics; not to mention they stay forever while Warp Siphons decay over time altho that should never be a problem due to 25 second timer
7. You can swap Seer's Presense for Kinetic Presense or Prescience if You have another Psyker in Your team so You don't lose on aura stacking!
8. Do not allow Yourself to reach 100% peril; instead stop smiting before it hits that threshold which performs a push that has enough stagger to give You and Your team extra time againts all enemies exept Crushers (can still stagger them but its very inconsistent; better not rely on it), Bulwarks, Reapers, Ragers and Mutants!

Thats about it! I hope you'll enjoy it as much as I do and change Your mind about Smite in general!