ZeBonk
 Zealot Build - Warhammer 40k: Darktide 

ZeBonk - all about that boss one tap (don't lie to yourself, you see that Slugussy and you know you wanna tap it)
After the changes you can still one shot Demon Host and Beast of Nurgle, almost one shot Chaos Spawn, and Plague Ogryn will live with 20%~ life.

Thunder Hammer
Perks: 

• Unyeilding - for that juicy boss one hit kill
• Carapace - The other thing difficult to one hit are Crushers and Maulers - this lets you do it.

Blessings:

• Thrust - Lets you one tap bosses
• HeadTaker - Much easier to stack then Slaughterer, and similar enough in power. 

Braced Autogun - Best use is to clear our elites/specials that are in a horde (like shotgunners/gunners in a swarm of ranged units) as Hammer struggles to kill high life targets surrounded by trash mobs.
Perks:

• Flak - Elites and specialists are difficult to kill in a horde with Thammer so use this instead
• Maniac - Specialists and Ragers in hordes are key targets

Blessings:

• FireFrenzy - helps to increase the weapon damage
• Speedloader - a lot more up time on the Autogun when you need it. DeathSpitter is a good alternative.
   

Immolation Grenade is going to do a LOT of work for you. When the boss (or other key targets) are in a horde, this is your only way to clear the trash giving you a free shot.
This will also kill Bulwark quite quickly, just make sure not to drag them out of it.
These are your primary clutching tool, make sure you are using them and using them well.

Inexorable Judgement - Unforunately the damage does not apply on the first his, luckily you don't need it to one shot bosses. I find it to be a very consistent and defensive option that fits the Hammer well.
Inebriate's Pose Lets you quickly build stacks in combat, and at 10-20 stacks you get huge attack rate buffs that the Hammer really needs. Combined with Retributors stance which I like as the hammer is sub par at killing hordes, and allies can very easily steal your kills and keep you from regenerating toughness. This gives you an incredibly consistent toughness generation that only requires you to hit an enemy. Also Pious Cut-Throat is wonderful for regenning your Ability for monster Auric missions.

Hammer doesn't have particularly high Finesse (Critical hit damage modifier) so Blazing Piety is meh.
Martyrdom works if you want a more aggressive - I find the lack of consistent toughness to make life hard with the Hammer.

ShroudField - This lets you one shot some bosses as long as you hit them from behind if you have Perfectionist.  Make sure to have the shot ready as you only have three seconds, and  your movement speed goes to nothing when you start winding up the power attack. Wait for obvious boss animations - like the Plague Ogryn stomp, or when the Demon Host is stationary finishing off a downed ally - where you know they will be an easy target.

I hope Loner gets some love, as I would love to spec into They Wrath Be Swift without having to give up so much toughness. Punishment is another great option to prevent your heavies from being interrupted.