He may know nothing about Shadows or the Dark Hour, but Casey knows plenty about hitting the other guy hard enough to be sure he goes down before you do. ("The other guy," in this case, isn't really the best word for it, but he doesn't know much about semantics, either.)

The voice catches his attention, though not enough to get him to turn his head (because you don't take your eye off the ball, that's stupid), and he takes a step back, bat still held in front of him warily. Backing down on a fight isn't really in his nature, but the amount of abuse that thing has already taken does support what he's hearing.

And he's not really sure what he even ought to be targeting, given the lack of distinct anatomy.

"What is this thing?"

She sounds like she knows some shit. Might as well ask.