Thunder Hammer
 Zealot Build - Warhammer 40k: Darktide 

This is actually a generic Thunder Hammer build I've used since the system change long ago when they added these tree builds updated now with the new Tree. Still experimental but was highly effective prior to the last FS tree rebuild, I was rolling 950K damage games with it prior, I doubt it will change now. 

And to be completely honest, my ranged weapon changes depending on the mission needs and party. I have used Bolter, Bolt Pistol, Flamer, Las Rifle, Recon Las Rifle, and even Auto Pistol (with proper Blessings). Also of note, the specific tree choices do not have to be exact either. There are somethings you really have to have, such as Purge the Unclean for damage against Unyielding and Infested for one shotting Crushers, Bulwarks, Reapers, etc, and soloing Monstrosities... and Restoring Faith for the heal regen for a de facto damage resistance from . Also you will want Holy Revenant for the immunity on taking damage that would kill you and the slight bump in health regain after still killing things. Also Martyrdom for the increased damage as you lose health. 

NOTE: You will want to take Bleed for the Emperor and Faiths Fortitude for the damage resistance per wound pip and +2 Wounds. What this does is that each wound "pip" or square will give a 40% damage resistance on the hit taken on the end of that pip, with 5 wounds at the end of each you have a 40% damage resist on end of that "pip" hit. While you will never die (even in Auric) due to taking too many wounds and getting back up (I never have anyway). Think of this more as an extra layer of damage resistance per pip. It makes it really hard for anything to even down you in the first place. Zealot is the ONLY class that works like this. 

The real key though with any Thunder Hammer Build is Vicious Offering, +10 Toughness restore on Heavy attack kill. Everything you do with Thunder Hammer is a heavy attack. Whether that's the Horde Side to side swings, or One shotting something on an Activated Heavy Attack. So you tend to be at full Toughness in any melee situation no matter what. When combined with Damage Resist from Faith's Fortitude (40% per pip), you end up really indestructible in melee. 

Weather you take the Stun Grenades or the Immolation Grenades doesn't matter really as they are both effective depending on what you want to do with them. I just prefer Immolation as it clears the way for a lot of one shotting of Elites while clearing the trash around them.  

I do miss Swift Uncertainty at the bottom of the chain as I most often find that the enormous numbers of shooters on some Auric boards are so over the top they are the absolute bane of my existence, and are really for most zealots. 

ABOUT THUNDER HAMMER Mark II: I doubt this will ever be a truly popular weapon despite the fact it is one of the most powerful and hard hitting weapons in the game that on Activation Charge is capable of taking upwards of a half chunk or more out of a Plague Ogryn and other Monstrosities and capable of soloing a Demonhost (which I have also done)... because it is also the hardest weapon in the game to use or master.

First of all, the swings are the complete opposite of every other weapon. You don't use quick left click strikes except rarely. You use ALL heavy swings which are big and slow. Luckily they changed the Activation Charge swing now to an Overhead so you don't waste it on some little trash mob by accident that gets in the way. You have to understand "the rhythm" of the Hammer.

 Rhythm of the Hammer: When facing a Horde you don't just left click an hit each one individually, its an actual Rhythm you hold for your heavy swing as they're coming in... then dodge to the left and release your swing as you step the side... the Hammer is a remarkably powerful tool that is not stopped by body mass except on an Ogryn, it will cleave through the whole horde knocking them all down even if it doesn't kill all of them. Then you cut in, while holding for another heavy swing and dodge back to the right while releasing your swing cleaving into another huge number of them. You can take out an entire horde all by yourself, by continuously shaving it with the dodge to the left then dodge to the right into your heavy swings. Or you can hold a doorway all to yourself. This is th Rhythm of the Hammer... it is a slow, steady heartbeat with the occasional push to knock them back into the group so you can continue to shave it away until its gone. Very few will ever have known this other than the other old players from Vermintide 1 and 2 who used it back in the day, and fewer still will ever master it.