The scene that I am thinking of in the ‘Magik’ miniseries is takes place in issue 4, page 14, panels 1, 2 & 3. Illyana has just tried and failed to make another acorn (her final attempt). Ororo’s oak, not Ororo herself, dies and Illyana watches as it “begins to crumble to dust”. In the comic we see Illyana’s thought bubbles where she says: “I want vengeance! Ororo created life for its own sake. I sought it as a means to and end – the utter destruction of my tormenter. Could that be the answer? Not a metaphorical weapon – as Ororo sought – but the REAL THING?!” From there it tells how Illyana cast her Master Spell, using all of the strength she took from the oak and all of her own. When she plunges her hand into the energy sphere, the Soul Sword was created. With it she goes on to defeat Belasco and return home through one of her stepping disks.
That is how it happened. What I suggest is when the oak crumbles to dust she thinks “I want to go home! Ororo created life for its own sake. I sought it as a means to an end – to escape my tormenter. Could that be the answer? Not a metaphorical escape – as Ororo sought – but the REAL THING?!” If that was what she really desired, her Master Spell may have given her a way to return to earth without creating the Soul Sword or any thing else. In the original, her mutant power is locked down by Belasco and is only restored when she shatters the enchantment used to Imprison her in panel 8. The ‘What If?’ has her running from Belasco, not having him defeated. It shows her having strong magic, but not being able to create. It shows her full of Rage and Grief and Hatred, releasing it after she defeats Belasco not in Limbo but on Earth.
It is my suggestion that the change I suggested would be logical for the story told in ‘What If? Magik’. That’s just my opinion, I could be wrong.