Twilight Sparkle finds Sci-Twi’s Spectrometer in her castle. It was the same one that was fully repaired by someone who wants the princess to become the same thing. She puts it on, and sees that it can light up on it’s own. A few minutes later, she shows it to her friends, and they started to like what she has on. The princess of friendship enjoyed her time wearing Sci-Twi’s device for an hour, until one of her books on the shelf lit up. Twilight gets it, and she noticed that it was Sunset Shimmer who wrote this letter about the device.
 
Dear Princess Twilight,
 
There is something I need to warn you about, and its the spectrometer. You see, the Human Twilight created this device, and started gathering magic from Canterlot High. She become an evil she-demon obsessed with magic. She opened up several dimensional rifts to Equestria, but I managed to use the magic of friendship to save my world, and turned Twilight back to normal. I have some brief information from Delta Brony. He said that Princess Dark Matter repaired the device, and carried it into YOUR world, so she can have you transform into the same thing that the Human Twilight became!! I know what its capable on doing!! Whatever you do Princess Twilight, DONT PUT IT ON!! Because if you do YOULL DESTROY EQUESTRIA AT AN INSTANT!!
 
From, Sunset Shimmer!!
 
Twilight dropped the book and said, “What? But how did Princess Dark Matter managed to carry the device into Equestria? We defeated her!! Unless she did it before we got a chance to vanquish her.” Suddenly, the device opened up, and the magic that was inside of it started to surround Twilight. She said, “What’s going on?! What is happening?!! Aaaaaah!! Noooooo!!” The swirling magic takes over the princess of friendship, causing her to fall unconscious.
 
When she woke up, she became fully corrupted with “Midnight Magic.” Her eyes were light green, and her pupils were violet just like Midnight Sparkle. She says a couple of words, “Ugh… everypony… help… me!!” But the device takes full control on the princess, allowing her to seek out magic in Equestria and draining it. The ponies must save her from her dark corruption, before she becomes the one that Human Twilight became.
 
I wanna say thanks to Miss Golden Dragon for making the Possessed Twilight vector for me.