Illyana (who apparently got migrated to Island M/Proto-Utopia with the rest of them, rather than being sent home to Siberia which might be the more sensible thing) triggers a device that sends her to a strange realm ruled by Belasco. The X-Men follow, fight Belasco and mostly win, but unfortunately end up with a 13-year-old Illyana, who has lived in Limbo for half her life, rather than the 6-year-old one that had run off. What has she learnt from Belasco in the mean-time, and more to the point, how on Earth are they going to explain that to her parents? While the last issue is providing the inspiration for BtVS, this then is Connor. She's got a medallion that'll go off when she hits womanhood and do all manner of unspecified sinister things, too.
This all only happens due to the X-Men being stupid. They've settled on this island that has risen from the deeps and has unusual architecture and is of unknown origin and have not even yet thoroughly explored it. The fault must be laid squarely at the doors of Professor X and Storm - both of whom were in a position to order the island to be checked out, and neither of whom did.
We get another name for Illyana this issue. She is "Illyana Natalyanovna", which along with the fact that she keeps calling her brother "Piotr Nikolievitch" implies that they don't quite understand how Russian names work yet. Apart from your basic first, given, name and surname/family name, Russians have a middle "patronymic" name, derived from the first name of their father, with -ovna (овна) or -evich (евич) appended. Natalyanovna is what, a matronymic? Which you might get for someone of unknown paternity. So not our little snowflake, then. Additionally, we're not sure what Russian name "Illyana" is supposed to represent. Ульяна (which might usually be translated Ulyana), possibly. Who knows?