Nuclear Psyker
 Psyker Build - Warhammer 40k: Darktide 

Explosion trick:

• we need 5 wounds (3x +1 wound curio)
• we need ONE +5% HP
• we need Crystalline Will 

Effect: when we go critical and explode, we will get to at least 2 wounds. Even if we eat overhead we will be picked up with 2 wounds and full HP.

Instead of using Blitz or staffs we go for melee and warp slash. First reason is that we are close to enemies when we explode, second reason is better control over when we explode (we trigger explosion with warp slash when at 100%).

Scaling:

• Warp Siphon keystone is here to give us up to +24% dmg, not to make Skill more available
• Bolt Gun with Lethal Proximity blessing expands our explosion range - more enemies will take full damage for being close, more enemies will be staggered by being far
• We make use of Soulblaze in two ways: 1) spreading flames between elites create chain reaction that kills whole squads (via Perilous Combustion and Wildfire) , 2) it enables us to keep Warp Siphon at max stacks (because of In Fire Reborn )
• We add Malefic Momentum  to get up to +25% dmg for our explosion from melee kills
• We also get offensive talents: Penetration of the Soul (optional, gives rending), Focused Warp , Warp Rider , Vulnerable Minds , Perfect Timing 
• We pick Kinetic Presence - more crits or cooldown reduction does not boost explosion, we warp slash not that fast to make crits valid option

How we fight?

Activate Scrier's Gaze to start ramping up Perils and gain defenses and damage for melee. Fight like a normal melee psyker, use Warp Slash if possible. When you have big group around you, you can go nuclear - use slash or block, then use slash at 100% perils. You need to time it, so while you scream no one damages you. If you get cought by poxhound or mutant while going nuclear you will still explode (saving yourself from special). If you don't want to use nuclear option - feel free to use Scrier's Gaze and fight in melee. When you see incoming large group of elites - prepare to get nuclear and start fight with that explosion. When you go to save someone - explode, then pick up (explosion will kill closest enemies and stagger other). From time to time you will get down. When you rise - you will be even stronger (because you will still be at 2 wounds, but healed).

In best case scenario, we have 20% rending from Penetration of the Soul , full bonus from Malefic Momentum - 25%, full bonus from Warp Rider - 20% and 6 stacks of Warp Siphon - 24%, Perfect Timing - 15%, if you managed to get Scrier's Gaze buffs and explode within 1,5s-10s window between end of skill safe window and end of buff - you get another 30%. And this is only what you get yourself. And remember - explosion ignores armour type (so Carapace will take same dmg as Unarmoured).

Can we increase it even more? Alone - you can take Smite with Enfeeble  and optional Charged Strike to increase dmg taken by 10%.

Remember that other team members will also apply their buffs and debuffs - our best friend is Skullcrusher debuff, but also other debuffs applied via abilities like Nuncio-Aquila (our nuclear psyker pairs well with N-A because of big AoE).

In the end, we are very able to stager and/or kill big waves of Maulers and Ragers. Even if someone survives, the cascade of soulblaze stacks will burn them to ashes.

Warning:

If you get to last wound - you need to use green stim or get healed to remove corruption from 2nd wound.

Teamplay Warning:

This build can be irritating to other people - sounds of screaming psyker are not the most favourite sounds in the game. Also, this build is not reliable enough to be used in clutch situations.

Tested on Auric and Auric Maelstrom, 5 full runs. No deaths. Occasional downs due to bad timing (overhead while going nuclear).

Inspiration:
I am atomic from Eminence in the Shadow: https://www.youtube.com/watch?v=gnGr21FAwo0