Classic Zealot build to win Havoc 40
 Zealot Build - Warhammer 40k: Darktide 

Here is the build with which I have the best win rate in Havoc 40. I honestly think it's one of the very best builds in the game for Havoc and it doesn't even require you to be insanely good at the game to work with it.

Reasoning is simple: take everything that helps you surviving and SURVIVE.
Your team utility is huge:
- 60% dmg reduction to anyone who starts taking dmg with a 8s cooldown thanks to Shield of Contempt 
- corruption resistance thanks to Beacon of Purity 
- golden toughness thanks to Chorus of Spiritual Fortitude 
- 10% crit chance thanks to Infectious Zeal 
- 15% dmg thanks to Blinded by Blood 

Artemia Mk III Purgation Flamer will give you the satisfying kill feed filled with your name and the dmg to justify you're actually useful (even though your auras alone were insanely good already).

Maccabian Mk IV Duelling Sword gives you the ability to kill elites. Make sure to stack uncanny strike!

Use Chorus of Spiritual Fortitude anytime you see an ally lose too much toughness or to get out of sticky situations. You can also use it to push into a room full of gunners: combined with the flamer, you can actually wipe entire squadrons. Chorus is NO LONGER a simple comfort spell because CDR got nerfed.

I don't take Ecclesiarch's Call nor Holy Cause because the uptime is too bad but if I had to pick one, I'd probably pick Holy Cause.

You are the backbone of your team, you both can play aggressively or protect & save your allies.
If you're not last survivor of your team with this build, you're doing something wrong.

Your worst enemies by far (especially in Havoc40) are Reaper . I even consider replacing my 21% hp with another 17% toughness or add an additional 20% gunner resist because of them. Be wary of them.

Talents to consider taking:
- Backstabber opens a much shorter path to the tree and is very good to kill Beast of Nurgle and Mutant that you just dodged
- Purge the Unclean very good dmg both melee and ranged against very common enemies
- No Respite stamina is always very good but I'm not sure it'd matter that much as Retaliatory Defence is already broken
- Prime Target one of the few talents that give both sustain and dmg but sometimes doesn't matter when you spend too much time running, it's also useless against bosses
- Hubris good DR that is easy to trigger but costs 2 points
- Relentless Fervor gives both mobility and stamina, very good for surviving but your team won't match your speed
- Sustained Assault big melee dmg

Talents to consider dropping:
- Anoint in Blood I honestly don't know if anyone would want to get rid of that as Flamer is too *damn good* but feel free to drop it and take Backstabber instead to preserve the tree pathing if you want
- Enemies Within, Enemies Without huge toughness regen tool that I feel has big impact (especially against bosses) but I don't think it's vital either
- Blood Redemption same as above, it is a nice toughness regen qol
- Against the Odds I love it personnally as it allows me to wipe hordes without taking hours or using flamer
- The Master's Retribution saves your clutches from dogs and helps not taking dmg from ragers but useless against bosses, feel free to drop it if you like other talents more
- Retaliatory Defence I'm honestly not sure which between this and No Respite is better but personally I stick with it
- Infectious Zeal honestly I shouldn't put it here as it's one of the best team skills in the game but if you just want to feel good about your solo plays, go ahead...