Only fools, madmen, and adventuring parties go into the Malpheggi, the swamp beyond the Everfree Forest. It can be left as an exercise for the reader as to which of these categories Samus Marcus (a Thyatian swordsman, or so he says) and Ivan (his companion in trouble) fall into. When they are rescued by the registered adventuring party, the Elements of Harmony, a grand quest across the D&D world of Mystara begins. Together they face culture shock, international politics, romance, dungeons, and a dragon with a grudge as Marcus learns how to trust his new friends and make up for his past mistakes while the Elements of Harmony try to save Equestria from a threat which proves more... complicated... than they originally thought. Also, pie. And hats. A D&D (Mystara)/MLP Crossover.

A human stays among ponies, mystifying them with his odd traditions and customs. It will be five years before Celestia and Twilight can send him back to his homeworld. Until then, Twilight wants to study him and have him experience pony culture. These are their stories.

He has faced the impossible...and failed against the impossible. He has had the chance to return to his home, only to sacrifice the chance for the sake of others. He is the prince of a fallen kingdom who has given everything to make up for the past. But now the samurai's journey takes him to a land of peace and friendship, where he has one more chance to make it back to the past. One more chance to undo the future that is Aku.

Written after season four. And yes, Jack will be a pony. In the past crossovers I've kept them as humans and for this one I wanted to try something different.

I own nothing.

This story is a sequel to Stardust

Times are changing for Equestria as Twilight’s return brings with it news of people and cultures from beyond the peaceful world everypony knows. Aid and volunteers are freely offered to help the besieged humans of Earth because every Equestrian knows that’s what good friends do. Unfortunately, making friends can also have the unintended consequence of making enemies.

When the monsters besieging the humans strike at Equestria with a level of brutality not seen in over a thousand years, the cry for help is sent to all the kingdoms of the world. Honored allies step forth to fulfill ancient treaties and oaths. Enemies, old and new, bury their grievances. An alliance never before seen in Equestria will be created to combat the monsters from the void.

And because of these events, a grim but welcome sibling to the XCOM project is born.

(XCOM/FiM Crossover)
(Sequel to Stardust, which I recommend reading before starting this. Fortitude Amicitia and Broken aren't required reading but are supplemental to the storyline)
(Gore tag for blood and violence)
(Alternate Universe tag because of the divergence from canon that Stardust has caused)
(Uses elements of Season 4)
(Coverart produced by the amazing Carnelian!)
(Many thanks to Arzoo, BradTheBrony, Vandenbz and Setokaiva for prereading!)
(As of 03/07/2016, the prereading team consists of Arzoo, BradTheBrony, Noble Cause and Metallusionsismagic!)
(Complete with it's own TVTropes page as part of the Stardust continuity. Could use some updating!)
(Character tags will be added as chapters are added!)
(Featured 5/12/2014! Thanks folks!)
(Possible spoilers in the comments! BEWARE!)

Diablo Crossover.

The Archangel of Justice destroyed the Worldstone to spare Humanity the corruption Baal infected it with. The force of its death knell shatters Mount Arreat and sends Tyrael hurtling across the endless planes of reality. He falls upon a world untouched by Angel or Demon, far from the sight of the High Heavens. So far, in fact, that he fears he will not be reborn from the Crystal Arch.

Wounded and near death, hope appears in the form of two strange creatures bearing the power of night and day.

Tyrael now faces a time of recovery as his power slowly heals within a body fashioned for him by his saviours. Justice Incarnate tastes for the first time the life of a mortal, and it is a strange, confusing experience .He has been left in the care of one Twilight Sparkle to learn of this world.

After all, where better to find peace and harmony than Ponyville?

Act I - The Root of Evil
Act II - ????????
Act III - ???????
Act IV - ???????

[Cover image used with full permission of the owner. Go on, go have a look at Chagial's stuff.]

Isolated from her friends and taken prisoner in the middle of a war, Twilight must deal with the very real dangers of being percieved as an enemy as well as the nightmares of her arrival on 'Earth'. Can she overcome her own fears and the fears of her captors? Will the wayward unicorn's assistance be a boon or a curse to the 'humans?' Most importantly, will she ever find her way home?

"In short, it's a story of friendship and plasma rifles, with the emphasis on the friendship. The characters are well written, the XCOM setting is fleshed out very well, and the story is compelling. If you love XCOM, you'll love the story, but even if you've never heard of it, it's more than worth giving the first 3 chapters a read.

There's excellent action later on, but the real strength lies in the collision between the friendly and naive world of Twilight Sparkle and the desperate world of humans fighting a losing war for survival and willing to do anything to turn the tide."

--Arzoo

(XCOM/FiM crossover)
(Cover art commissioned by a friend and created by the magnificent FoxInShadow!)
(Original cover art by the amazing Carnelian can be viewed here!)
(Gore tag for blood and some violence)
(Many thanks to the studius OminousTen, Arzoo, xXFluttershyForeverXx and finally Setokaiva for giving my rambles a once-over)
(Now with it's own TV Tropes page! Get to tropin' folks!)

The history of Equestria spans dozens of centuries, and many terrible foes have risen up from the past to threaten the future once more, only to be defeated.

When a vicious and powerful enemy older than any Twilight, her friends, or even the Princesses have faced before returns, they will have to reach out to an ally just as ancient for help... but is she still the heroine she once was?

This story takes place after the end of Season 3.

Honourable Mention: Best Fimfiction, Pony Awards 2013

Full-Cast, Illustrated Audio Drama version by Scribbler Productions can be found here!

Hardcopy editions from Ponyfeather Publishing can be found here!

King Sombra’s dark influence was obliterated by the Crystal Heart, and the villain is well and truly dead. But when he attempts to steal the afterlife of an innocent victim, a human spirit is left hurtling towards Equestria, where this unfortunate soul is revived into the only vessel available: the reconstituted body of King Sombra himself.

Thus, a cheerfully oblivious alien is crammed into the form of the most evil and malicious being Equestria has ever known. Not that Shining Armor and Cadence know this, of course. As far as they are concerned, the King is back and he’s lost his fricking mind.

Click here for the TV Tropes page!