“Marvel’s Hulk: Where Monsters Dwell,” the first animated, feature-length film centered on Hulk, premieres on Digital HD on Oct. 21. In this spooky, action-packed feature, the Green Goliath and Sorcerer Supreme team up with the Howling Commandoes, a supernatural strike force, to thwart the villainous plan of Nightmare, the evil, supernatural lord of the Dream Dimension.