Pre Alicorn Twilight, AU tag is for very minor things. (Writing started before season 4, so everything after that is considered non-canon for this world)

Every 7 years, 9 weeks and 3 days, the stars align just perfectly creating a line of stars to power Luna's teleportation spell to a different world. A world that nopony knows about, not even her sister. This specific day has come up, and Luna has recently been having horrible nightmares and needs a few days off. But when Twilight interrupts Princess Luna's spell on accident and she is sucked along with Luna to this planet they are unable to return to their home. For seven years. This planet is not safe either, oh no, it is a very primitive version of their own world in fact. Ponies are not advanced and have no modern day ethics or civilizations, many warring city states and small empires plague the beautiful world, and it is these groups that will challenge the two ponies past the brink of exhaustion, both mentally and physically. These two will need every ounce of strength to survive, and Twilight will be exposed to things she never could have imagined. They need to get back home, and as soon as possible, for there is terror brewing on both worlds, both here and back home.

Normal Twilight, Dark tag is light dark, no torture or things like that. There will be action however, and some mild descriptions of wounds and what not. no more dark tag

I did not create this picture nor do I own the rights to it. If the artist would like me to take down the picture and replace it with a new one, please contact me via PM and I will take down the picture within 24 hours.
Picture found here: http://cyberdrace.deviantart.com/art/Ambassador-of-the-Night-338278046