I think Magik sacrificed herself to separate Limbo from Earth. And as a "parting gift", left her family and friends with her original 6 year old self before she was corrupted by Belasco.
However, this is the fun thing about comics...One story can be interpreted many different ways. Just from this thread alone, I know people have their own interpretations and ideas of who Illyana is...
Is the current Magik the original Illyana or just a carbon copy created by Belasco who stole Illyana's soul?
Is Illyana a teenager, a young adult, or ageless?
Is Illyana straight, gay, or asexual? Is her true love Kitty Pryde?
When it comes down to it, everyone has a different idea of who Illyana is, and I think that is pretty cool & something sort of unique to this character.
Just for the record, my Illyana is the original. A young adult. And she is NOT Kitty's soulmate