It was a simple process that was hard to screw up.
Sometimes the mortal races would get a little uppity. It happens. All she had to do was sleep for a while until things cooled down and she could continue along her way.
Except something went wrong. Ridley slept for too long, and Equestria is like a whole new world.
Now it's just a question of whether she feeds on it, or Equestria chews her up and spits her out.