Red Zone Psyker (Beyond BubbleDome)
 Psyker Build - Warhammer 40k: Darktide 

Place your Bubble (Telekine Dome) over a large group of enemies that you plan to hit with your sword. Or place it where a large group of enemies that you want to hit "Will" be in the next few seconds. Then get in the bubble and hit things with your sword. 

I ripped the idea for this from a build here on gameslantern that was called "beyond Thunder Dome" or something similar. 

In this build you use your weapon special Warp Slice and Assail to build your peril. Assail can be useful to switch to quickly and pick off Disrupt Destiny targets early to help start building stacks. 

You can swap out Assail and Ethereal Shards for Brain Rupture and Kinetic Flayer, still useful for building peril and picking off marked targets, however not so reactive. Kinetic flayer (when below 80% peril) will potentially heavily damage/pick off an Elite or Specialist once every 8 seconds. 

Remember, this build operates best at 80% + Peril 
 

While not a hard and fast rule, your Bubble should be used to designate a space you fight IN. The bubble with Sanctuary is a tremendous toughness boost at 10% per second. Also if you are within its area when it expires you gain a 5 second 50% Toughness Damage Reduction. 

You should also be at 80% + peril so you should be getting 33% Toughness Damage Reduction from One with the Warp as well as the 5 Second buff from Sanctuary. 

Pick a new spot, place your bubble and FIGHT. 

A note for your Telekine Dome that Telekine Shield teaches. You do not always have to put the Dome immediately over your head.

The Dome is placeable cover, it is a tool to deny ranged enemies. Use it to advance across wide open space. some portion of it just needs to be between you and things shooting at you. 

Also, incase you did not know, it blocks Beast of Nurgle Vomit attacks. Brilliant to avoid the debuf that grants and then being eaten by the slug.