Warlock refused to listen to Magik, and absorbed the life glow of two demons. Just as she looked like she was about to attack, Magik transformed her outfit into that of a normal little girl. She refused to attack Warlock. Since he could not betray his own pacifist mutation, Warlock melted into a useless puddle. Magik picked him up & began to explain her plan. Using a scrying pool to watch Storm fighting Karma's hold, Magik observed as Karma threatened to permanently twist the souls of Storm & the New Mutants so they would behave like this normally.
Approximately 20 years earlier, a little African girl with white hair & blue eyes stole the wallet of a bald American man. Professor Xavier used his telepathic powers to retrieve his wallet, and sent Storm on her way. His attention was then drawn by a telepathic being inside a local saloon. Magik & Warlock observed events from a side-alley, amazed that Storm really had been a thief. They moved over to a window and watched as the Professor telepathically defeated Amahl Farouk. Both New Mutants observed the high energy levels, even though they didn't truly understand what had been happening. Magik correctly deduced that Farouk's consciousness didn't die and that it was his consciousness that he had become the Shadow King, who currently held Karma in his thrall. Magik relied heavily on Warlock for her plan, and when he agreed she gave him a big kiss of thanks.
Back in the present day, the Shadow King released his grip on Storm briefly to torment her with his plans to permanently change her personality. He planned to use Storm & the New Mutants to defeat Charles Xavier, but was interrupted by Magik's appearance. Magik said that she was willing to join the Shadow King, and they shook hands in agreement. However, the Shadow King refused to let go until Magik opened her mind to him. As the two struggled, the other New Mutants slowly teleported away. Once they had all been sent to Limbo, "Magik" melted and transformed into Warlock.
The Shadow King realised that he had been tricked, but it was too late. The teleportation back to Limbo had broken the telepathic control over the mutants. They quickly attacked. The Shadow King briefly attempted to take control of Wolfsbane, but Mirage tried to use her power against him again. However, instead of an image of Professor Xavier, they saw a scene of war torn Vietnam.
Karma had been returned to her own mind, and briefly it appeared that they had defeated the Shadow King. However, they realised that it had been too easy, and that the Shadow King must have been hiding inside the mind of one of them. Magik drew out her Soulsword, claiming that if she concentrated hard enough she could use it to kill. She went to lunge at Storm, but changed direction at the last minute. Cypher reeled in horror as she slashed him, and the New Mutants could all see that he was really possessed by the Shadow King. Storm then leapt on Cypher, while Karma finally managed to attack the entity who had turned her own power against her.
Karma faced the Shadow King on the Astral Plane. There he presented her with her own glutinous desires to tempt her back into his control. Even on the Astral Plane her body was obese, but sheer strength of will made her break from from the hold the Shadow King had on her. Her Astral form shattered, revealing a skinnier version of herself underneath. She then punched the Shadow King in the stomach, causing him to balloon in size & eventually explode.
The Shadow King had fled. However, upon returning to the physical world Karma was still hideously obese. The nightclub had burst into flames during the fight, and Karma begged to be left to die. However, all the New Mutants and Storm escaped. As they watched Pharaoh burn from a nearby rooftop, Storm invited them all to stay with her on the Aegean island of Kirinos for a brief vacation.
Note: The events here are directly followed up in New Mutants Special Edition #1, followed by Giant-Sized X-Men Annual #9. These should (ideally) be read before New Mutants #35.