Gandolf's 'Havoc Vampire' Bubble Voidblast
 Psyker Build - Warhammer 40k: Darktide 

A build crafted not unlike the Inferno build I made for Victor, but, with as stated within that build, swapping In Fire Reborn for Psychic Vampire and then using a Trauma staff. Either of which can be used in Havoc to great effect, it's all in a manor of preference. 

Your goal stays the same, CC everything, kill everything you can from range, and slap down as many bubbles as you possibly can manage. This build doesn't crit asss much, so instead of taking mettle, I swap it for Warp Expenditure so there's still a good trickle of toughness flowing in at all times. But beyond that, sword shove and slash anything that gets close, get it away from you so you can go back to Voidblasting everything, and protect your team with bubble after bubble after bubble. For the sword, heavy attack any special that gets on you, or light light light heavy the wave/push attack into horizontal light into heavy diagonal if it ever gets to dense. You're preferably Trauma staffing the whole time, but in moments of many pushes needed panic that should be your flow.

Rending Shockwaves also has the added benefit in making your team able to kill things that much better too, so it can be a nice thing to have when going in with two Psykers especially. Knock everything to the ground, weaken it for yourself and your team mates, and burn everything haphazardly along the way.