New X-Men: Imperial

Professor Xavier's School for Gifted Youngsters has never been busier, and the threats against X-Men have never been more deadly. As mutantkind enters a bold new era, the challenges they face become even more extreme! John Sublime and his U-Men continue to press their attack against the mutant heroes, but there's a far worse danger on the horizon as Cassandra Nova returns - this time with the incalculable power of the alien Shi'ar Empire at her disposal. Collecting New X-Men #119-126