I cast gun (Now meta)
 Psyker Build - Warhammer 40k: Darktide 

This used to not be a meta build, but strong and fun. Now with the improvements to disrupt destiny it has gotten so much stronger.

The strongest spell is the bullet, and all the heretics will know your warp shenanigans is only to strengthen your bullet.

Quick rundown of how to play this:

1. Your revolver is used to kill elites and specials, you'll one shot most with a weakspot hit, with crushers and maulers you usually have to double tap them, and don't worry about taking your time to line up your weakspot hits, you get more crit chance from the revolver's blessing.
2. Sword is backup for weaklings, mainly you'll use your shards to clear hordes, just keep an eye on that peril level and don't use your shards if they risk hitting daemonhosts. Melee weapon is the only thing I haven't experimented too much with in this build, meaning you can probably find a better alternative, but noteworthy about the catachan sword is the ability to parry which is great for ragers especially.
3. You are squishy, so very, very, squishy. Meaning you always have to watch out for weaklings taking your down in melee. In ranged you have good survivability with your talents, shield and 1 shotting of specials. 
4. You suck at killing bosses, you are support for your team when killing bosses. You're the guy taking down specials trying to disrupt your team while they're fighting the boss. Always have some ammo ready for the specials.
5. USE YOUR SHIELD, low cooldown, stops weaklings and elites ocassionally, specials, stops suppression, it's just so good.
6. Is your revolver not doing enough dmg? Build up peril with assail then fire away, with the nerf to assail you'll often use your "ADS" mode with assail for more peril with less shard usage. Just make sure to have your revolver loaded for when it's go time.

Not recommended to use in ammo slurping teams, you want the majority of the ammo. Some final words:

How was disrupt destiny buffed? It simply does what it says in its description now. Shocking, I know.

Sadly while Perfectionism turns you into a god of death at 30 stacks, I've found it through testing to be too unconsistent. Perhaps with a faster reloading weapon with a faster rate of fire it could be a good choice, but for the revolver you need flexibility to kill enemies other than your Disrupt Destiny marks for more than 15 seconds.

The unspoken strength of Disrupt Destiny is it being an automatic tagger for you, meaning you'll find enemies easier in low visibility and or when theyre hiding. But it will also sometimes trick you into shooting at a marked enemy just to find out the enemy is behind a wall.