When Trixie tried an advanced teleportation spell, she was expecting to pop up in the next town. Instead, she found herself in a creepy base on a strange planet... A research station full of humans who were also experimenting on teleportation and about to open a portal that should have remained closed forever.

A portal that ended up linking Equestria and the shores of Tartarus...

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This is a Doom 3 crossover. Because why the hell not ?
(Consider that Equestria Girls never happened for this fic. Only one human world at a time...)