Dead by Daylight

I recommend giving the "Slingshot Tech" a try.
Severed Hands + Festering Carrion.
Severed makes it so that Swarmed survivors make nearby survivors swarmed if they get close to them, and Carrion makes the cooldown between launching your birds and having a refreshed set of 3 to shoot out slightly faster.
Perks:
Lethal Pursuer (9 seconds of aura reveal at the start + 2 extra seconds on aura reveals by any means)
Barbecue and Chili (Aura reading on survivors who are 40 meters away from the hook)
Discordance (Let's you know when survivors group up on gens)
BloodWarden (gives you the opportunity to snipe people sitting at the gates).

Video on the tech:
If sniping isn't working, bringing Carrion with Thick Tar (slower bird repel time) and go with a more aggressive build. Put the birds at windows and pallets and force survivors to walk into them.

Good luck.

This achievement requires you to down 50 survivors WITH the crow special attack. You can either down a survivor by launching a crow at them at close range, or you can launch a crow at a damaged and swarmed survivor to down them (at any distance). The latter is much harder to do.

I just unlocked this achievement and there are two ways to get it quickly:

- Damage a survivor first with your basic attack, as this is very easy to do. Chase them and keep throwing crows at them, eventually one will be close enough to down them (when crows hit a survivor that is close, it will damage them straight away). I managed about 10 downs in a single game by doing this.

- Message a survivor before the game starts and ask them to let you down them. They will often expect to be allowed a free escape after this though.

The alternative is to just keep playing as the artists and get the downs naturally. Depending on skill level, this could take a long time.