When the Harmonic Chaos Incident merged Mobius and Equestria into Mobequestrius, the human world went through some changes to match. So, when Twilight's crown is stolen and taken to another world through a magic mirror, she, alongside Spike, Sonic, Sally, and Hope go through the Mirror to the human world. There, they meet human counterparts of their friends, as well as a human counterpart of Sonic himself, and have to work together to retrieve the Element of Magic.
