As I told you before, I was thinking of representing her, Ahuizotl and Mane-iac through event cards. - the ones characters draw when travelling beyond the portals. These may include situations arranged by them that the investigators have to beat by rolling tests. They may also involve actual combat with the villain as a monster - but their tokens wouldn't be added to the random monster pool, they can only be encountered through events (kind like in the original game you can bump into Cthulhu in Rlyeth even when he isn't the old one for the game)
Sunset Shimmer
The previous student of Princess Celestia, Sunset Shimmer was a very talented wizard, but way too ambitious for her own good. When she was caught secretly researching a magic mirror said to be a dimensional gate (which Celestia had told her she wasn't ready for) it looked like her education would be over. RAther than be expelled, Shimmer subdued the guards and used the mirror, travelling to a world that turned out to be a reflection of Equestria populated by humans. Since the portal only activates under specific conditions, she was trapped for several years in human world.
While there, she was in human form and had no access to her powers. When the portal reopened, she emerged from the mirror and managed to steal Twilight Sparkle's crown, the element of magic. However, when she escaped back through the miror, she dropped the crown, which was mistakenly delivered to the headmistress of the local high school, becoming the prize for the queen of fall formal.
Twilight Sparkle went through the portal to recover the crown and was likewise turned into human. She met the human equivalents of her friends and tried to recover the crown with their help.
Powers and abilities:
In Equestria, Sunset Shimmer is a powerful unicorn wizard.
In human world, she managed to establish a human identity - she had no access to magic, but could use indirect methods of attack (such as filming Twilight's initial failures at behaving like a human and putting them on youtube). She had two first year students (Snips and Snails' equivalents) as lackeys.
In the finale of the movie she got her hands on the element of magic and discovered that outside of Equestria it was prone to being subverted - she managed to control its powers enough to gain access to magic - enough to briefly turn herself and her mooks half-demonic and mass-dominate normal students. However, when she tried to hit Twilight and her new friends with a fireball, the element recognized the bonds of friendship that defined it and refused to hurt its rightful owner, turning against Shimmer and depowering her.
