A cannon seems redundant as most vampire lore allows them to fly or transform into something enabling flight. Maybe a cannon is for rapid deployment of vampires? The question then is how do you prevent immolation during firing?

Yep Ancient Egyptians used crocodile dung among other things.

And now you know

At some point the bard will get out and then they’ll be 🎶 Coming out of my cage and I’m doing just fine… 🎶

I’m sorry, I’ll see myself out