Illyana Nikolievna Rasputina was born on the Soviet collective farm called the Ust-Ordynski Collective, near Lake Baikal, in Siberia. She was the youngest of three mutant siblings. Illyana's brothers were the X-Man Piotr (Colossus), and the cosmonaut, Mikhail Rasputin. As a child, she was saved by Piotr from a runaway tractor, just before her brother was recruited into
Miss Locke captured Illyana along with several of the X-Men's other loved ones to get them to rescue Arcade from Dr. Doom. After they were freed, Colossus allowed his sister to stay in the United States, believing she would be safe and not be used as a government tool like their older brother Mikhail had been. Professor Charles Xavier touched her on the head, giving her the ability speak English.
At the age of six, Illyana was kidnapped by Belasco and taken to Limbo, where the X-Men followed. While there, Illyana also ran into alternate versions of the X-Men, who had not been able to return to their own dimension. While attempting to return to her own dimension, Belasco grabbed Illyana; Kitty Pryde held her arm, until she lost her grip, letting Illyana be taken by Belasco. He told her he loved her and turned part of her soul into a Bloodstone, giving her great potential for power and allowing him to control her. While staying with Belasco, Illyana was constantly beaten by Belasco's servant, S'ym.
Illyana was rescued by Storm and Cat, alternate versions of Ororo Munroe and Kitty Pryde. For a while, Illyana was instructed in magic by Storm, and instructed in combat, by Cat. Illyana had to constantly battle demons and some of that reality's versions of the X-Men, including Nightcrawler, to survive. After attempting to return home to her reality, Illyana eventually became Belasco's apprentice, while secretly gaining advice from Storm's astral form. Cat had been turned into a true house cat and was loyal to Belasco. Belasco attempted to use Illyana as a pawn to bring about the Elder Gods. At this time, Illyana's own mutant powers of teleportation discs were discovered. Illyana was forced to kill Cat to save the life of Storm, whom she later killed to save from being used in Belasco's sacrifice. After burying Storm, Illyana briefly teleported home to her parents farm, where they did not recognize her. She returned to Limbo, where she magically caused her own life force energy to manifest the Soulsword and defeated Belasco. A simple looking blade upon its origin, the Soulsword began to develop intricate designs and forms upon itself the more Illyana used it, becoming more powerful with each use.
Illyana returned to Earth only seconds after Kitty had lost her grip on Illyana's arm. She had spent years in Limbo while only mere moments elapsed on Earth. She was thirteen, now the same age as Kitty. The two became roommates and grew very close.
In the School for Gifted Youngsters, Illyana was tutored by Professor X. Illyana joined Kitty in Stevie Hunter's dance studio. As Magik, Illyana joined the New Mutants and trained in the use of her powers in the Danger Room. Illyana quickly learned that she was not nearly as powerful a sorceress on Earth as she was in Limbo, but retained an immunity to the most powerful telepathic probes and she continued to struggle with the use of her mutant powers, often sending people to the wrong place or time.
Belasco made an attempt to recapture Illyana by sending S'ym after her. After the New Mutants were overwhelmed, Illyana secretly used her magic to defeat S'ym and had him swear allegiance to her.
Illyana learned that when she summoned her Soulsword while on Earth, an eldritch armor would cover her body, starting with her left arm. As time went-on, the armor would cover more and more of her. In order for Illyana to be an effective sorceress she was forced to teleport most of her enemies to Limbo, where she was ruler. Many times she would teleport demons from her realm to Earth to aid her. Eventually Illyana revealed that she was a sorceress to her teammates and her brother.
source: http://www.angelfire.com/comics/benriely/
http://marvel.wikia.com/Illyana_Rasputina_%28Earth-616%29