Health
 Zealot Build - Warhammer 40k: Darktide 

Summary:
Big hp pool. Take hits. Deal good elite/boss damage, and use flamer for hordes that are getting out of control. Chorus of Spiritual Fortitude and Stunstorm Grenade for emergencies.

Weapons:
Use the Crucis Mk II Thunder Hammer heavy attacks for all trash/horde clearing. Use the special powered heavy attack for an overhead for all elite/special/bosses. Note: Make sure to hold the heavy all the way for Thrust. Once you get used to it, feel free to release as soon as it hits 3 stacks.
The Artemia Mk III Purgation Flamer is used by holding down right click to aim/prep it, and then holding down the left click at the same time to release a stream of fire. The left click by itself is a short puff with slightly higher stagger, but it is largely useless. This weapon takes time to switch to and prep with the right click, so make sure to have the necessary space or foresight when needed.

Spare Points:
You have 3 spare talent points.
- Restoring Faith : Costs 2 points. Lets you survive a bit longer and helps recover from mistakes. If you keep taking damage, this will help a lot.
- Sustained Assault : Costs 2 points. Realistically won't help boss dps that much outside of the 5% stat node, but will help in every other situation with free 25% total melee damage.
- Good Balance : Costs 1 point. The buff is VERY short so it might seem meh, but it gives damage reduction which also affects your health.
- The Voice of Terra : Costs 2 points. This lets your flamer generate toughness for you, so clearing a big wave will full heal your toughness if you get low.

- Vicious Offering : Costs 0 or 1 point. This lets you use your melee more comfortably as the slow swings usually cause you to take chip damage if you do not perfectly dodge/push hordes. You should be using heavies for cleaving hordes anyways. If you take this, consider replace Bleed for the Emperor for the talent point. Bleed for the Emperor helps mitigate major damage taken such as overheads or snipers. Depends on what you have the most trouble with.

- Backstabber : Costs 1 point. 20% more damage to bosses if you hit them from behind. Have to play around it, but 20% is 20%.
- Maniac : Costs 1 point. If the heavy attacks of the thunder hammer are too slow, this will help a bit with another 12% attack speed.
- Duellist : Costs 1 point. The crit damage buff is almost useless in this build and the buff is short, but it is 50% more weakspot damage for those large special heavies.

In Depth Explanation:
Feel free to skip this

Martyrdom gives you melee damage buffs, and with Faith's Fortitude you can stack up to 24% melee damage. You could run wound curios to raise this damage, but I tried to make this as comfy as possible until you are more experienced. You end up with a LOT of max hp with this build so that you can go to one wound left more comfortably. Keep in mind, you should not go to one wound early on purpose, use your hp not waste it.

Until Death and Holy Revenant will help you stay alive AND stay at one wound. 25% of max hp is the perfect amount when you have 4 wounds total. Thy Wrath be Swift will have it so that your thunder hammer attacks cannot be interrupted which is a huge quality of life. Purge the Unclean will help your horde clear and monstrosity damage. This will let you use your melee for hordes more comfortable while buffing boss dps at the same time.

The Flamer is there when the hordes are starting to overwhelm your team, or if there are a lot of ragers. The Flamer will not kill big armored targets that well, but you can clear the trash around those elites and one shot them with the special heavy attack of the Thunder Hammer. 

This build does not need to worry about refreshing short buff timers or being forced to play a certain way. It covers both hordes and elite/boss killing well, but can suffer from ranged gunners and ranged specialists.