Sashimi Zealot
Build for Darktide

Build Info

Pros: 

• One-shot muties with a weakspot hit and a few momentum charges (easy to get)
• Some of the best horde-clear in the game, great for when you're paired with only psykers and vets.
• Tear through the "waves of muties" maelstrom condition with ease
• Shooters are not a problem
• Give groups of ragers the quick death they don't deserve but by the Emperor's mercy. 
• You are extremely useful in pretty much any situation the game throws at you

Cons: 

• Low boss damage
• Reliant on ranged and blitz for carapace

Strategy

• In a horde, try to clear trash off your teammates. Killing enemies from behind will quickly charge up your ability. Use a heavy every once in a while if you need toughness.
• Against Armor, Alternate between Heavy 1 and your Special, the special has very high stagger (but not enough to stagger a crusher anymore)
• Dodge often to keep up momentum stacks. 
• There's only a little wiggle room for the damage breakpoint in 1-shotting Muties. I have a 80% damage, 77% first target, and +20% Maniacs perk on mine and need about 6 stacks of momentum to 1-shot them, which I'll almost always have. First target is the most important stat for this. 
• Use your speed to clear flanks as you move forward so that your backline can do their jobs untroubled. If you don't then all the trash you left behind will go attack them in addition to specialists and whatever else spawns behind the team. When that happens you get no support up front. 

Alternatives

• The blessing Rampage is almost as good as Deathblow on the mk VI, as the power buff adds enough cleave to kill 2 poxwalkers with each light attack and makes it easier for a single heavy to kill ragers. If you roll Rampage I'd just keep it and reroll a perk instead. 
• Bolter is a great choice for this build as well. It's great to crash a wall of ragers, maulers, crushers, etc. or the weakspot of a Beast of Nurgle, but its slow draw speed leaves you vulnerable against gunners and ranged specialists. 
• Heavy Sword IX is also very good. Its attack chain is quite different so it's up to personal preference. Deathblow is mandatory on it. 
• Heavy Sword VII is like the VI but with inverted attack patterns. It's harder to use against Muties but you have the Heavy + Special combo for mixed hordes which is sorta useful. 
• You can swap out Momentum for Martyrdom if you want, it's useful but not as consistent. 
• Instead of Thy Wrath Be Swift, you can take Punishment and whatever else with it.