The divinities of the Yog-Sothoth Cycle of Myth, are native to a semi-insular complex of planes adjacent to the Material Planes. Within this complex are a Parallel Material Plane, a shadow plane coterminous with the Parallel Material and a large adjacent plane known as the Dreamlands, which serves as both an Afterworld for the Material Plane, and a home to an indigenous population as well. Transport from this complex to the Material Planes, or vice versa, is accomplished through the shadow plane and either the astral or ethereal planes, to which the shadow plane is also adjacent.
Within this complex of planes, an extended clan of deities has ruled since time immemorial. Their great power may in fact be attributable to their monopoly over an entire set of planes. Aeons ago, however, war broke out within this clan over an ethical dispute related to the permission or proscription of Black Magic. Its opponents, known as the Elder Gods, narrowly defeated the advocates of Black Magic, henceforth known as the Great Old Ones. Defeat held an awful price for the Great Old Ones: all of the divinities in this complex of planes have among their available avatars one Primary Avatar, which is the only avatar that may operate within their Parallel Material Plane, and which cannot leave their home complex. With their defeat in this great War, the Primary Avatars of the Great Old Ones were imprisoned by the Elder Gods under the power of the greatest magic that they could devise, the Elder Sign. As long as the Elder Sign is efficacious, it is sovereign in controlling the Great Old Ones and their supernatural minions; however, as the warring factions were so nearly equal in power, even this greatest of magicks has only temporary effectiveness. One day, when the stars are right, the Elder Sign will lose all power over the Great Old Ones, and they will once again be free to do as they please within their domains.
