Zealot who forgot to take pills
Build for Darktide

Rolls and perks are not 100% perfect, but close enough to not matter much.

If you want to swap out the MK X for the Mk II, make sure the Mk II is equipped with Dum-Dum and Infernus. Ghost is not necessary due to the higher attack speed and lower ammo usage means you can consistently proc Empathic Evasion.

With the knife, you want to use push attacks constantly. They have the damage profile of the heavy attacks, but are much faster. Kinetic Deflection makes you lack of stamina not matter, and your quicker stamina delay means you can constantly push attack.

For fighting ragers, use Assail to stagger them, then headshot them with the knife.

For Maulers, build up Uncanny stacks then headshot them with the push attack, or shoot them in the chest.

For Crushers, pop Gaze and start push attacking their heads. 

For Bulwarks, wait for them to attack, dodge to the left, and push attack them from behind. You should be able to get 2-3 hits in if they don't get staggered. You can also toss Assail shards above/behind the Bulwark, then activate the aimed mode to make the shards hit the bulwark from behind, which will stagger it. 

For muties, stab them and dodge at the same time. On a crit, you can 1-shot mutie swarms, and it may be possible to do so with a headshot. Against regular muties, it will take more than 1 crit, but a crit headshot or follow-up heavy will finish them off with the bleed.

Against hordes, mix assail with the knife. Since Uncanny Strike persists after sheathing your melee, you can have the rending apply to your Assail shards, though they can't build up the stacks themselves.

Against gunners, if they're distant you headshot them with the laspistol, or use Assail. If they're not too far, you can rush them with the knife to lock them in melee. 

Against Reapers use the las pistol and shoot them. As they're basically stationary, headshots should be astoundingly easy.

Against bosses, either shoot their weakpoints, or dance around them with the knife. WIth the Mk X using the knife is preferable, with the Mk II the pistol is preferable. 

Difficulty order from easiest to hardest is Plogryn -> BoN -> CSpawn normally.