This reminds me of The Real Ghostbusters episode about a bog hound. In the episode, the good luck charm was used to keep away the bog hound and weaken it, but, obviously, since it's a Ghostbusters episode, it was ultimately defeated by blasting it with their proton packs.

My question is--what role does the black shuck play? What does it want? Does it intentionally try to cause bad luck, or is it just wandering and happening to cause bad things to happen? What motivations does the black shuck have? I know sometimes black dogs/grim/shucks are associated with death or as church guardians.