Days Of Future Past

All comics in this event are on Marvel Unlimited. If you are familiar with the characters you could get away with just reading issues 141 and 142.

Comic	Comments
Uncanny X-Men 138	Basically recap of all comics to date.
Uncanny X-Men 139	Mainly introduces Kitty Pryde, side story with Wolverine.
Uncanny X-Men 140	A few pages with more Kitty, mainly finishes Wolverine's story.
Uncanny X-Men 141	Main story starts in this issue.
Uncanny X-Men 142	Main story concludes in this issue.
Uncanny X-Men 143	Not really part of the event, Kitty solo fights a Demon monster.