Bat Swarm

They're no Stellaluna...

So, let’s say you have to think of a vampire. What’s the first thing that comes to mind? Why, tall, dark gloomy castles in the middle of the night. And what creature inhabits these castles aside from their undead masters? Why, bats of course! But these aren’t any normal bats - due to the fact that they roost in the heavily dark magic-saturated castles of Sylvania, they are massively swole and aggressive bats.

These are the Bat Swarms, and they are... well, swarms of bats summoned by the Vampire Counts to war. They come in thick black clouds that often blot out what little light there is, somewhat akin to Batman strategically releasing a ton of bats whenever someone comes into the Batcave - intended to disorient the foe so that the real heavy hitters can swoop in for the kill., whilst getting in their own hits through clawing and biting where possible (and presumable also giving rabies).