This is a paperback reprint of Marvel Masterworks: The Uncanny X-Men, Vol. 2 (available on Amazon.
As part of my continuation reconciliation with the X-Men I picked up the second Uncanny trade. I still love that Wolverine isn't very prominent, although by the end of these stories he is starting to become less of a raging asshole and more of a two-dimensional character.
In this volume of the Marvel Masterworks series we follow the transformation of Jean Gray into Phoenix. The X-Men fight in a wide variety of settings, and it was very cool to see them in space!