Crucis Piety Build
 Zealot Build - Warhammer 40k: Darktide 

Crucis doesn't need a damage keystone, allowing you to spec into Blazing Piety to take advantage of Zealot's crit synergies. Righteous Warrior isn't needed - 20% crit chance is enough to keep all of your talents online - so you can take Stalwart for an extra 25% Toughness DR plus some extra toughness replenishment on kill (hidden talent property).

You can easily drop a couple of talents if you feel the need to take Thy Wrath Be Swift. Choose between some combination of Disdain, Purge the Unclean, Anoint in Blood, Stalwart and Enduring Faith, depending on how much you prioritize specific types of damage vs. defense.

Out of the gate, with absolutely no temporary damage buffs from any source except Thrust stacks, Crucis 1-taps every elite in the game except Crushers, who annoyingly live with 32 health. In practice, this will almost never happen -  a single stack of Sustained Assault is all that's needed to get you over the finish line. 

You have a couple of choices on Crucis. One is Slaughterer vs Headtaker. Neither is needed to reach elite 1-taps, so I chose Slaughterer, as it deals more damage and lasts longer. Theoretically, Headtaker lets you get bigger bonks on Monstrosities in a vacuum, but it's probably a net DPS loss from just bonking them twice, and besides, Monstrosities in a vacuum are a complete non-issue. Remember to dodge before bonking to trigger Duelist.

Another choice is Unyielding vs Maniac perks. Unyielding helps with boss bonks obviously. Maniac gives you light 1-taps on Dreg Ragers and Mutants with Slaughterer and Sustained Assault stacks. This probably isn't worth it on its own, but +Maniac also helps with just the fairly miserable uncharged Maniac damage. If you have Annoint in Blood, Maniac also allows your throwing knives to 1-shot Dreg Ragers (although this works for your ranged weapon as well).

Ranged weapon is personal preference. I like the Laspistol for mobility and defense against shooters. It also synergies quite well with the +15% crit from Piety. Unarmored perk is needed for 1-taps on Dreg Shooters. Shooting Flamers with this gun is never a good time - prioritize using your throwing knife against them.

Curios are personal preference. Block efficiency is very good and quite underrated IMO. You block all the time in this game. You block when you push. You block when you revive. You block when you can't dodge. You block when you're in a tough spot and need to buy time. Getting block broken is one of the worst things that can happen to you, and block efficiency helps prevent that. Thank you for attending what you thought was a Crucis build but which was actually my block efficiency sales pitch.