The Other Side is a mysterious realm, and the home of demons. It is the source of all magic, and a Magus reaches into The Other Side to use High Art. Some call it hell, the world below or the underworld.
Long ago before the Old Time, it is said, the our world and The Other Side were one and the same. Demons roamed the Circle of the World and left chaos beyond imagining in their wake. They bred with humans, and their offspring were half breeds; half-human, half-Demon. Almighty Euz was one such Devil-Blood. His blood granted him great gifts in Magic. He rose up against the Demons and banished them to The Other Side, and sealed the gates between; thus allowing humans to flourish. It is said that the intensity of his battle shaped the land.
To prevent the world from ever knowing such tyranny again, he proclaimed The First Law; "It is forbidden to touch The Other Side direct. Forbidden to communicate with the world below, forbidden to summon Demons, forbidden to open gates to hell." Demons are said to be made of lies, always seeking to be freed from their banishment.