It is unknown when magicians from our dimension discovered the shadowy realm called the Otherside or when these sorcerers began consigning enemies into its ethereal reaches.
Since the first recorded reference to it in 794 BCE by an unnamed priest of Amoun-Ra, the Otherside has served as the de facto prison for a mage’s most powerful opponents. It has also been reported that the Otherside has been used as an extra-dimensional storage tesseract for artifacts whose magic is considered too devastating to remain on the Earth plane, such as the Ark of the Covenant.
By all accounts, travel to the Otherside is so easy that a novice magician can cast a spell to open a portal to it. However, it is nearly impossible for a portal to be created while within the confines of the Otherside. To date, only the mysterious sorcerer named Hades, arch-enemy of the golden-age Dr. Arcane, has successfully returned from banishment to the Otherside.