The distraction allowed him to watch the movements of the creature more closely, even as he tried to think of other spells he could use on it. He'd need to try some combination of spells to counter Dark magic, spells to control animals, spells that affected wizards. The light bothered it, but it didn't stop it. And scurrying up the wall and onto the ceiling wasn't something he'd expected at all, what a bizarre combination of traits.

He pointed his wand and cast a sharp, "Immobilus." Maybe if he treated it as an object, he might be able to freeze it in its tracks.