The purple ball came into existence when the Traveler was gravely injured. It was an attempt by the traveler to capture and destroy the heart of the Darkness. As the people of earth fought with the Traveler against the Darkness, the Traveler used some of its light to create a vessel for the Heart of Darkness, the source of the Darkness's power. This prison would become the purple ball. The Traveler became to injured to complete the ball. While the Heart of Darkness was captured, its power could still extend beyond the sphere. Over time it has corrupted the minds of guardians in an attempt to free itself so that the Darkness can return to its former power. Only the guardians can complete the travelers work and destroy the Heart of Darkness. Doing so will weaken the darkness and its allies. So I ask you guardians to resist the purple balls power and destroy it. Do it for your fellow guardians and the people of Earth. Do it for the Traveler. Do it, for The Light. Edit: [spoiler]The soccer ball is the missing component of the prison.[/spoiler]