"Ashes"
The battle for NYC and the one between Madelyne and Jean is over but Sinister is still on the loose as they find him hiding at Professor X's mansion. The teams split up and make their way to the mansion as each team encounters the survivors of Sinister's Marauders. But Sinister gets the last laugh as he uses Polaris/Malice to round up both X-Men and X-Factor members and stuns them with the exception of one member who stands in his way, Longshot.
Continues in X-Factor (Vol 1) #39.
Reprint that came packaged with the Marvel Legends Wave 10 Mr. Sinister Action Figure