The Multiverse.

Infinite worlds. Infinite possibilities.

An ancient being by the name of The Exiled has been traversing the Multiverse in search of something. Something that will give him unlimited power over all. He has been recruiting villains from all over to do his bidding. Once he locates what he seeks there will be none to stop him.

But when Twilight Sparkle joins forces with 4 other heroes from various dimensions, his plans are put at risk. It would seem that this Unicorn is more of a problem than he thought.

Join Twilight as her and her new team of friends traverse through various worlds to beat the bad guys, and to put a stop to The Exiled and his nefarious schemes.

Read the various adventures Twilight has Through The Multiverse.

This is a fic based on the Time Loop Files, the format of which was first codified by Innortal on fanfiction.net.
Here's a brief guide.
The basic idea is, one character (the Anchor, usually the main character of a fictional setting) is looping back to the very first moments of their parent series every time either they die or some kind of time limit expires. They of course end up monumentally stir crazy given enough time.
Eventually others start to loop as well.
The reset is not always perfect. Sometimes a loop's history will be different to the "prime" loop, or canonical plot.
"Crossover" or "Fusion" loops also occur, randomly. These can involve the home loopers having a guest, or the anchor for one universe spending time in another, or replacements of one character by another.
Vacation Loops are where the Anchor (or others) decide/s "buck it" and lets off steam by doing whatever comes to mind. There's little or no attempt to maintain the original timeline.

In addition, and particularly more recently, it should be known that this story has a collaborative element to it - people may submit loop ideas or loops, ideally at the Spacebattles thread (a link to the current version of which is on the Trope page), and they may become included.

There's two page image options, thanks to Filraen - the current page image has been edited by the original creator from this work of theirs.. The other one is here:
http://hourglass-vectors.deviantart.com/art/MLP-Loops-466030169

With the barrier broken and the Monsters free, Asriel Dreemurr is apprehensive about what he knows is coming. He won't be able to maintain his form for much longer, and is afraid of no longer being himself again.

Then, a mysterious figure offers him a deal. A second chance, an oppurtunity to redeem himself... but the figure chooses where he gets that second chance.

Not wishing to become a Flower again, Asriel takes the chance, and is transported to a whole new world of magic, wonder, sights no Monster has seen, and of course, the magic of harmony and friendship.

And into whose hooves does the figure send him the young Prince to? Why, the hooves of someone else who has been given a second chance, and seeks to redeem herself and make up for the mistakes of the past. None other than the Princess of the NIght, Luna herself.

Come along as the young Boss Monster does his utmost to make good use of this second chance, and along the way, find family in a land far from his own.

Awesome cover by Cyaneworks over on Furaffinity~!

Has a companion story right here, Hopes and Dreams at Canterlot High

EDIT: (Featured *numerous times, seemingly now after each update lol*)
Thank you thank you thank you aahhhhhh you're all amazing

This story is a sequel to Knowledge is Power

Three years have passed since Twilight Sparkle disappeared into Apochrypha, followed by her friends. Will Equestria have changed in their absence? Will Apochrypha have changed them?

An unknown future awaits, but whether it will be bright or dark is something known only to those who have the gall to claim they are a higher being, and even that might not be enough to foretell everything.

All the while, something from the distant past returns.

Cover art provided by https://www.fimfiction.net/user/866/Cold+in+Gardez

My little pony is owned by Hasbro

Elder scrolls is owned by Bethesda Softworks