Little is known about the blue-skinned warrior named Illumina. It is said that she is a descendant of the Gar refugees that came to Eternia after the destruction of Infinitia and that she was a member of the Guardians of Grayskull (a secret sect devoted to the preservation of Castle Grayskull’s secrets throughout time).

When the Sorceress of Grayskull and Man-At-Arms created the Mystic Wall to separate Eternia's Light and Dark Hemispheres, Illumina was trapped on the dark side. Fortunately, in addition to being a great strategist and possessing formidable fighting skills (especially with melee weapons), she has the power to control light and can even blind her opponents when those other talents are not enough. Prior to being caught on Dark Hemisphere, she assisted Dekker in the teaching of Duncan who would become Man-At-Arms

Much earlier in her life, Illumina was known to support anti-Eternian sentiments among her fellow Gar. Accordingly, she was a fierce opponent of efforts to integrate the Eternian and Gar peoples. Her role, if any, in the ruination of Captain Miro’s planned union with the mother of Keldor and the subsequent Gar massacre instigated by Count Marzo and other segregationists remains unknown. Whatever the cause, Illumina’s views changed with age and she eventually sought atonement and repentance past for her past.

Although a heroic force, she has been called very cold blooded. A common misconception is that her female mount is a descendant of the Battle Cats of old. In fact, her white-furred companion is an entirely different species that is genetically closer to the blood-thirsty Panthor.