Originally posted by playerofgames:

I'm wondering if they will shoot those flying things that drop crap on me (forgot what they are called) Gyill?

Gjall.

I'd use ballista for something like crowd control against seekers and bats, but I haven't tried them at all yet myself. How you put them to use probably depends most on what kind of base setup you have. If you rarely visit outside of a wall for example, then that could be good spot for one.