For 10 points, the god Morpheus has a realm over what sometimes prophetic events that usually occurs when one is asleep?
In Japanese tradition, the Baku was a creature which subsisted entirely on these objects. In Welsh legend, the occurrence of one of these entities prompts Emperor Maxen to send out his army to seek out a beautiful maiden whose name is Helen. One of these entities titles a section of The Mabinogion and appears after Rhonabwy resides next to a yellow ox-hide. In Greek myth, these events are governed by a realm with a gate of horn and a gate of ivory. The preponderance of these events forces Odin to ride down to Niflheim and question a volva about why they are inflicting pain to his son Baldr. A willow hoop often functioned as a catcher of these objects among the Ojibwe. A child of Nyx and Erebus also presided over these objects and was known as one of the Oneiroi. For 10 points, the god Morpheus has a realm over what sometimes prophetic events that usually occurs when one is asleep?
In Japanese tradition, the Baku was a creature which subsisted entirely on these objects.
dreams [prompt on "visions"; accept nightmares]