What we know for sure is that she was in an intense fight, most likely by herself, as she appeared by herselfm, against what was probably a small army, was engaged in close quarter combat and long range combat as she was beaten and shot, and that something got destroyed and was transported with her in pieces. I would guess that whatever she was fighting was being led by a magic user, otherwise she wouldn't have been fighting by herself. She did have a modern x-uniform, so she could have already been on a team, but I don't think she'd teleport away without her teammates. This may be what leads her to reform the New Mutants.
I still think its impressive that she held her sword with an arm that had three arrows in it.
BTW. I may kill someone at marvel if it turns out that Pixie is the one who did that. Not a chance, but Pixie will always hate Illyana. There may be a lot of fights between them, but Pixie is incable of EVER beating Magik. In the Pixie parade there are lines Marvel must not cross.