Mind Blower!!!!!
 Psyker Build - Warhammer 40k: Darktide 

The Mind Blower Overview

The Mind Blower Build is designed to rip and tear through dozens of elite enemies within a short window using Brain Rupture.

The entire build revolves around killing elite enemies quickly with the Brain Rupture blitz and rewarding the psyker for doing so with several talents that play off one another. 

Explanation of core talents

The core talents of this build are:

1. "Brain Rupture" - Blitz
2. "Kinetic Resonance" - Blitz modifier
3. "Psykentic's Aura" - Passive
4. "Empowered Psionics" - Keystone
5. "Overpowering souls" - Keystone modifier

A core component of this build is the "Kinetic Resonance" blitz modifier, which decreases charge time of the blitz for 10 seconds upon using the psyker's ability.

Another core component of this build is the "Empowered Psionics" keystone, which significantly decreases charge time and increases damage on the Brain Burst if the psyker has at least one stack of "Empowered Psionics". This makes it great at killing elites, even if they have carapace armor on.

The buffs from "Empowered Psionics" stack on top of the effects of "Kinetic Resonance", thus allowing for the psyker's Brain Rupture to achieve up to +100% damage and have a ridiculously fast charge time if the psyker has at least one stack of "Empowered Psionics" and just used their ability.

Thus this build benefits heavily from the  "Psykentic's Aura" passive and the "Overpowering Souls" Keystone modifier.

"Psykentic's Aura" reduces the cooldown time for the Psyker's ability whenever anyone, including themselves, kills an elite enemy.

"Overpowering Souls" instantly grants the psyker one stack of "Empowered Psionics" when they kill an elite enemy.

In short, elite kills buff the psyker's Brain Rupture which in turns makes it better at killing elites in a sort of feedback loop.

Additional talents

"Kinetic Flayer" can be used to get additional kills on elite enemies every 12 seconds. I use it as it is just more elite kills and further contributes to the feedback loop.

Although either "Kinetic Presence" or "Seer's Presence" could be used as the Auras of this build, I found that the additional damage against elites that "Kinetic Presence" grants makes it slightly easer to get stacks of "Empowered Psionics". Additionally, it makes it easier for allies to kill elites and thus "Psykentic's Aura" and its cool down buff is in effect more (which in a sense does "Seer's Presence's job).

Any of the abilities could be used for this build. I placed "Venting Shriek" as the ability on this build because it is simple and allows you to stagger enemies that get too close to you. Furthermore its ability to reduce peril allows you to do more brain bursts in the event you do not have any stacks of "Empowered Psionics". I can imagine a high peril version of this build revolving around the "Scrier's Gaze" talent and "Warp Rider" passive being utilized but I personally haven't tested it. "Telekine Shield" pushes this build into a more supporting role on the team that I think goes against it's heavily offensive abilities against elites, but I can imagine it to be fun for some players.

"Vulnerable Minds" passively grants +20% damage against Ogryns and Monstrosities, which will make it easier to kill them with your Brain Rupture. 

As you will be gaining and using a lot of stacks of "Empowered Psionics", taking "Psychic Leeching" is good for the toughness it will provide.

"Charged Up" will allow you to store up to three stacks of "Empowered Psionics" which is very useful when you get stacks from the 10% chance on kill. These extra stacks can act as a buffer when you need to use stacks but know you won't get an elite kill with one Brain Rupture (i.e. Crushers). However since you are getting stacks from "Overpowering Souls" and then immediately burning them on most Elites you don't' really need to store stacks 80% of the time.

Although "Kinetic Resonance" reduces peril generation and "Empowered Psionics" outright prevents it, there is a chance you will gain peril when they aren't in effect. Using Brain Rupture repeatedly without these talents, which occasionally happens, will actually generate a notable amount of peril. Thus I took talents that make quelling peril quicker, such as "Solidity" and "Warp Ghost".

Description of play loop

Upon seeing a group of elite enemies, the psyker will activate their ability and give them the charge reduction from "Kinetic Resonance". This will allow the psyker to quickly kill one of them and instantly gain a stack of "Empowered Psionics".

Using the stack of "Empowered Psionics" and the remaining ~10s of "Kinetic resonance" the psyker will be able to do several brain ruptures on the elites within a few seconds. Each elite brain rupture will give another stack of "Empowered Psionics" thanks to "Overpowering Souls" as well as reduce the time needed for the ability to cool down thanks to "Psykentic's Aura".

Even in the event that the 10 seconds of  "Kinetic Resonance" is not long enough to kill the entire group of Elites, "Overpowering Souls" will continue to be in effect and buff the offensive capabilities of Brain Rupture, thus still reducing the ability cooldown and wait for "Kinetic Resonance".

Flaws of this build

This build entirely revolves around killing elites with Brain Rupture, so when the psyker isn't killing any elites this build grinds to a halt.

If there is a monstrosity or a large group of Crushers, this build is still useful buts its effects aren't as apparent as it takes significantly longer to kill these enemies. This slower kill time means that "Overpowering Souls" isn't in effect as often and thus its damage buff and charge time decrease isn't in effect as often. Same thing with  "Psykentic's Aura", thus the psyker's ability will have a longer cool down. This is why "Vulnerable Minds" is a good passive to take as it increases the damage against these enemies.

The buffs this build grant to Brain Rupture can make it very good at killing specialists, however they do not contribute to "Overpowering Souls" on kill. Thus, sometimes killing a specialist can use up a stack of "Empowered Psionics" that could have been used in an attack on a group of elites.

If there is a horde of poxwalkers and groaners this build is useless. Killing a single horde enemy with Brain Rupture is barely impactful and actually wasteful if you have any stacks of "Empowered Psionics". Furthermore, due to how groups of enemies will walk in front of each other, occasionally you will waste a Brain Rupture on a non-elite enemy that walked in front of your crosshair, which is very frustrating in a tense situation. To mitigate this, I recommend to lean into your melee or ranged weapon in the event of a horde.