When the Boogey Man causes Grim to lose his powers, rank, and title in the Underworld Court for misusing his powers, he plots to seek out Horror's Hand and take over the world. It's up to Billy, Mandy, Irwin, and … Richard Steven Horvitz, Grey DeLisle, Greg Eagles, Vanessa Marshall, Maxwell Atoms, George Ball, Jane Carr Added on HBO 2023-03-05.