Xorn is a fictional character published by Marvel Comics.Originally portrayed as a Chinese mutant with a "star for a brain", he is eventually revealed to be the X-Men's archnemesis Magneto in disguise at the climax of Morrison's run. After Magneto is apparently killed in the "Planet X" story arc, he appears alive and well a few months later in 2004's Excalibur Vol. 3 #1, which established that Xorn never was Magneto.
The Xorns possess miniature stars in their brains, each having a primary state. Kuan-Yin's star manifested as a sun, while Shen's star manifests as a black hole, although Shen is able to more or less physically manifest his outside of his body. Kuan-Yin's sun was capable of emitting blinding light that could instantly incinerate another being. Shen's black hole emits an intense gravity field that not even light can escape. The Shen Xorn is capable of reversing his star's natural state. Being twins it's possible that Kuan-Yin could do the same thing too.
The Xorns can also feel the movement of energy and emotion on many scales. They possess gravitational senses that allow them to manipulate energy for a variety of purposes, including warping of gravitational fields, sensing when a death has occurred in their vicinity, shaking gravitational particles in the air around them to allow them to speak other languages, and to heal others. Given the nature of their mutant abilities, the Xorns do not need to breathe, nor do they require food or water to survive.