Summary by Robert Diehl. Thanks!:
Writer: Chris Claremont
Pencils: Jackson Guice
Inks: John Beatty
Letterer: Tom Orzechowski, L. Lois Buhalis
Colorist: Glynis Oliver
Editor: Ann Nocenti
Editor in Chief: Jim Shooter

Synopsis:

"Father's Day"

(Apr. 1987, 22 pages)

A techno-organic S'ym has allied with Magus to overthrow Illyana and rule Limbo himself. She uses her Soulsword to purge Limbo, splitting it and herself apart.

In space, the Starjammers are on a planet trying to buy supplies to repair their ship, when Xavier comes across Illyana in a slave market. He and Binary attack, freeing her.

On board the ship, Illyana describes the Marauder attack. Xavier, Lilandra, and Binary teleport with her to find the rest of the New Mutants, scattered in space-time. They arrive to find Limbo a paradise, purged of demonic influences. But S'ym is still in revolt and tells Illyana that he will be able to take over if Illyana ever removes her Soulsword.

Xavier, now able to access Illyana's mind, helps her teleport to collect the rest of the New Mutants back to the Starjammer, and they are immediately attacked by Magus. Xavier augments the powers of Amara to hold together the planetary crust, Dani to form an illusion of a strong Warlock, and Shan to possess Magus's mind. Doug and Warlock merge and enter Magus's head, and reprogram him to be an infant.