Spider-Man gets caught in the magical explosion at Dr. Strange's Sanctum Sanctorum and spends several decades in a magical dimension fighting horrors Man Was Not Meant To Understand, becoming horribly scarred. Eventually he finds a way back to his home dimension (possibly making a deal with some demonic entities), but ends up several months before Ultimatum. He then goes around undoing the bad stuff that lead up to Ultimatum, including beating up Magento and Dr. Doom.