H40 Support Nuncio Arbites
 Arbites Build - Warhammer 40k: Darktide 

This build shines in final toll missions, as well as when there is another arbitrator with break the line or a tauntrgyn. Even though it is a support focused build, you still pump out a lot of damage. I am typically 2nd highest damage in the game, behind chem scum or flame psyker. Controlling packs of elites through impact is your job, along with killing specialists via the dog or your slug shotgun. 

Not many people know this but if you hold the ability button when activating nuncio you can command it to move to a location. You can only do this when placing it, but its nice to send it across the room or around a ritual for example.

Fear of Justice and Suppression Force stack additively, which means enemies you have staggered or hit in the head thanks to Concussive deal 45% less damage, this is calculated against your damage resists and the result is the enemies doing a lot less damage. The attack speed reduction is also great for final toll, especially against captains since they really get crazy below half health. The nuncio damage amp is also multiplicative with other damage taken debuffs on the enemy and then multiplicative with your damage and power buffs. This leads to a lot of damage being done when combined with other dmg debuffs. Focus Target! , Warp Rupture , Soften Them Up , Valuable Distraction , Blinded by Blood , and Empyric Shock are all the ones I know of like this, so having any of these on your team is really good.

Hammerblow makes the loss of Forceful not as felt, it is still your job to knock the elites around and you need impact for that. Execution Order is taken for Malocator as well as wall hacks to take out specialists fast. 

If your team has strong boss damage you can drop Keeping Protocol in favor of something like Not Far Behind , Drive them Back , Rapid Movement , Rebreather , or Imposing Force .

Feel free to swap Execution on the maul to Thunderous . You will lose damage and the maul doesnt really care about brittleness, but your psyker will do a lot more damage. This is especially strong in rotten armor missions.