An undead Emperor in need of a new body. A Spartan lost in space. A ragtag team on a suicide mission. What do they all have in common? They all wind up on the magical world of Equestria, where war has been forgotten. That, however, is soon about to change.
When each of them is about to be retrieved, ancient evils arise to unleash hell upon the unsuspecting world. When the forces of three galaxies clash around them, can our favorite ponies hold out against the onslaught?
This is a crossover involving Warhammer 40k, Halo, Mass Effect and MLP, and is also my first fanfic. Comments and reviews are welcome.
Rated T for language, violence, and general adult situations.
Now on Tv Tropes!

Twilight Sparkle and her friends are called to Canterlot for the Summer Sun Celebration at request of Princess Celestia and stumble into a new and terrifying adventure with the discovery of an alien: a creature with an apparent vast intelligence and a strange case of amnesia. Now, the arrival of old friends, powerful allies and new dangers lead to a new age in Equestria- both for the better and for the worse...

Proofread and Edited by: _Demosthenes_
Image Owned by: Korbox

Memoirs of Insanity Series:
Part I: Precursors
Part II: Time

Currently being edited and rewrote to accommodate for the new Hyperverse Canon. Chapters completed: Two*

The storm is breaking on the Horizon.

It's been two months since the battle against Nightmare Moon. Luna is recovering, Celestia is busy turning the government back into a diarchy, and the Mane Six have returned to their lives. All seems well, but when Celestia discovers that half of the power of the Elements of Harmony have been transferred to each of the Bearers, she decides to send thirteen mysterious members of the Royal Guard to monitor them as they manifest and develop their new abilities.

The sins of a forgotten war still linger, and an ancient evil lurks in the shadows, just waiting for the right time to strike. The Mane Six suddenly find themselves once again at the heart of a conspiracy to bring about Eternal Night, and only by awakening their powers and realizing their full potential can they do anything to stop it. Friends both old and new will help them along the way, and an unseen force will guide them as it seeks to right a wrong made thousands of years ago. The Bearer's journeys will take them outside the borders of Equestria and into the world beyond, and when they return, they'll have the power and experience necessary to save the world and bring about balance in all things.

The Powers of Harmony TV Tropes Page (SPOILERS)
The Powers of Harmony Art

Thanks to Wildy71090 for the cover pic.

Two enemies wind up in Equestria due to a major mishap. Will they come to terms with this world? Most importantly, will they be able to put their old feud aside to survive?

Darth Vader is one of the most despicable forces in the galaxy. Once a powerful and respected Jedi Knight, he betrayed the Galactic Republic and Jedi Order for the dark side of the Force. The newly christened Sith Lord was apprenticed to Darth Sidious and quickly became a master of the dark side. Vader was soon the scourge of the Jedi, continuing the Great Jedi Purge by slaughtering all remaining Jedi.

An extension of Emperor Palpatine's will, the Dark Lord was constantly on the move, traveling throughout the galaxy to defeat rebel uprisings and kill any surviving Jedi. This mission brings him to the edge of the Outer Rim into the Unknown Region of the galaxy, in an unknown star system. High above an unnamed planet he duels with one of the last remaining Jedi in the galaxy in a starship battle. But during the battle his ship is damaged, and he crash-lands on the mysterious planet.

With his connections to the Galactic Empire severed, Vader must find a way out the land known as Equestria, inhabited by the strange creatures known as ponies. That, or he could take it over.

Luna has been plagued by nightmares since she was very young, her parents and sister are concerned when no known spell shows any sign of helping the poor filly. Suddenly however, her nightmares seem to vanish and she seems a lot more cheerful. She tells them that her new friend is keeping the nightmares at bay and teaching her new things, but they simply believe that it’s a simple imaginary friend.

But he is very much real in her dreams.

Whenever Luna falls asleep, she wakes up in her dream world where her friend, Crescent, teaches her the ancient ability of protecting the dreams of children as well as a race that has nearly been forgotten.

For his time in this world is coming to an end and Luna, his ‘Little Moon’, is to become the new guardian of dreams.

A story from Luna's childhood into adulthood, inspired by the cover art.

Thank you to Berry Punch, Bocaj518, Rainbowbob and DVAN56 for their help.
Cover art found here by dawkinsia.

Princess Celestia tires of constantly being surrounded by decorum, deference, and formality, and decides to take a day off from being Princess. But visiting Ponyville incognito is harder than she expects. Will she be able to fit in and make friends without blowing her cover?

This story is a sequel to The Flight of the Alicorn

Rarity was certain her troubles with magical gemstones had ended, but an unexpected royal visit soon convinces her otherwise. In order to save an ailing Princess, stop an ancient menace, and avert a disaster that threatens the survival of a lost tribe of ponies, Rarity, Blueblood, and a brave group of friends will travel to strange and foreign lands, and into the fathomless depths beneath tormented seas. In her quest to uncover the secrets of the Abyssal Forge, Rarity will have to use all her charm, wit, and skill—and rely on allies old and new—as the unlikeliest of ponies once again attempts to save the world in style.

Part Two of Three
The Adamant Triskelion - Book One: The Flight of the Alicorn
The Adamant Triskelion - Book Two: The Abyssal Forge
The Adamant Triskelion - Book Three: ???

Beautiful cover art by Lucky Dreams.

Twilight and her five friends are transported during a botched spell, across dimensions to... Ponyville, Equestria? But not the same one that they knew. Sitting on a bench is Harpsy and Babar. The Doctoress avoids apples from an aspiring Applebuck. And in a library across town, six stallions join their forces as they try to decipher the appearance of filly look-alikes of themselves around Ponyville!

There was only one explanation. For all of it. All of the strange, erratic behavior. Her irrational fear of the sun. Her nocturnal habits of locking herself in in the dark and closing all the blinds. Wearing her sunglasses everywhere, even inside! It was time to invest in some silver, garlic, and a wooden stake.