The Starlight World is an AU of Earth, with different levels of reality, known as Spheres. Each Sphere is governed by separate laws and energies, such as time, space, light, or even more abstract concepts, such as emotion. Some are more chaotic than others, and a many are filled with creatures of malice. The energies of the Spheres are what give the mages power to defend themselves from beings that have sought the destruction of mankind for millennia.
Of course, being suppressed for so long has made the beings of the other Spheres restless, particularly in the Dark Sphere.
The forces conspiring against humanity are growing, gathering behind a powerful mage that should have been defeated eons ago. The Darkness that grows within the world, and in the hearts of all, must be released.