Average H40 Bubble Inferno build
 Psyker Build - Warhammer 40k: Darktide 

Alternate Weapon:

This is for the Rotten Armour modifier

Rifthaven Mk II Inferno Force Staff: Perks +25% Carapace // +25% Flak. Blessings: Blaze Away, Penetrating Flame. Dunping Warp Resistance at 60%.

Role:

Your job in Havoc 40 is horde clear, support with bubble. Ideally you always want a front liner between you and the horde (Zealot, Arbiter, Ogryn). The gameplay is even easier than last patches: just light attack spam. Seriously, it pushes poxbursters, staggers ragers and maulers, freezes the horde. Be sure to drop the bubble at cooldown, if you are defending a point stacking two bubbles on top of each other is really effective at holding a position. 

Sword:

Generally you want to use your Dueling Sword to block, push and mostly to deal with crushers. DS got nerfed, they got buffed, but still hitting charged eavies on their head is the best way to kill them. 

Always be mindful of your escape routes. Poxwalkers really like to swarm you so be always sure to check your back and even commit to open a way thorugh the back horde and carve an escape route. You are the damage engine of the team, if you and a frontliner are still alive you can clutch your way out of every situation, in the current patch every inferno psyker should be the top damage dealer by far. 

This is a mainly ranged focused build so, while it's mandatory that you have some skill in melee in order not to fold from a couple of poxwalkers, don't spec any kind of damage into it. 

Inferno Staff:

A light attack spam can keep any human-sized enemy almost perma staggered. This combos very well with Perilous Combustion, Souldrinker, Empyric Shock and Kinetic Flayer. Most times you will evaporate entire hordes. This happens generally when a Scab Shotgunner or Dreg Gunner squad is inside and enemy formation. Perilous combustion's soulflame stacks can overcharge the regular 16 maximum, so when you flame in a horde with many shotgunners that talent creates a deathball of 30+ stacks on the entire horde, killing it almost instantly. Use the secondary attack when facing monstrosities and ogryns, as it puts the stacks on them faster. 

It is useful to always stay above 50% tapping the quel button in between 2-3 light attacks will generally keep you afloat while maximising damage output through Warp Rider.

Brain Burst:

Its main use is to kill distant gunners and specialists. A good combo you can do with a vet is for him to highlight Poxburster with Focus Target! for you to burst with one charge. Dealing good damage to the horde. However burst is very slow, use it only to kill problematic specialists other people in the team can't deal with in time.

I don't like to get more toughness regen. Firstly you are not supposed to get hit, second it is your job to maximixe bubble uptime, so just sit in there and block/light spam, if you need more toughness swap Wildfire for either Essence Harvest. When playing the other staff you could teorethically swap Empathic Evasion for Anticipation, but i never do.