When both Zuul and Vinz Clortho are both active, they can work together to bring Gozer to Earth, and provide them with access to the world of the living. In Ghostbusters: Frozen Empire ...

Zuul—the creepy, dog-like demon with red-eyes who is a minion of the evil Gozer. It was a fun throwback to the original Ghostbusters film, but he wasn’t as appreciative of the nostalgia as I was.