MLP/Undertale crossover.
Not a PWNY-verse story.

Long ago, the Monsters and Humans fought a great war. The Monsters lost, and were sealed in the Underground. It would take the power of seven human souls to break the barrier that kept them imprisoned. They only had six. And so the Monsters waited and hoped, praying that another human would find their way to the Underground. Some thought the seventh soul would give their King the strength to break the barrier. Some dreamed of a human who would be their friend, and save them all...or had nightmares of one who would bring back the war.

...but nobody came.

...but somepony did.

Eons after the war, with no way to tell how much time had passed above, a tiny blue filly with wings and horn fell into the underground, calling for her Mama. None knew the poor creature's nature or origins...but her soul was powerful with magic, even more so than a human soul.

None can know what will come...of this little 'Woona'.

Cover art by Sanyo21

Uncle lives a very fulfilling life at his antique shop. It's peaceful and quiet for the most part, just how he likes it. Of course, he's a skilled chi wizard, so he knows better than to actually let the universe know that he's content. So he complains.

A lot.

Then one day, a basket containing three infant magical ponies arrives, and his peaceful life goes out the window...to be replaced with, perhaps, something a little more than contentment.

The universe, apparently, is smarter than he gave it credit for, because now he has "Three More Things!" to complain about to hide just how much they mean to him.

------
Part of the PWNY-verse.

First chapters take place approximately 10 years before the events of the first episode of the show.

Edit: Cover Art put together by Shadow Bolt
Edit 2: New Cover Art by Swan Song. Link to his page in image source.
Edit 3: Level Dasher commissioned an image of the CMC with their new Cutie Marks from Katakiuchi4U over on Deviantart. Here's the pic!

Heavy spoilers for Undertale

Once there were two races that ruled the land, ponies and monsters.
One day, a war broke out, killing thousands in the process.
The ponies had won, sending there enemies deep underground, and trapping them by using there magic to create 'The Barrier'

Years later, an alicorn foal with a sun for a cutie mark wakes up,
Only to find herself lost, not knowing who she was.
The Story begins.

So, this was inspired by many of tatsurous story's check them out out if you want to.

Re-edit: Seeing this cover art... FILLS ME WILL DETERMINATION
Also,
OH MY BUCKING GOD! LOOK AT THAT BEEEAAAAUUUTIFUL COVER ART MADE BY enamis. I couldn't thank you enough for making such a fabulous cover art I can't believe I was your inspiration (I felt so important) but that doesn't mean I left nightglimmer22 for trash, ooohhhh-nnnooooo, here's her cover art as well [img]http://s29.postimg.org/60p4zg793/image.jpg[/img]
I cannot thank you people enough you fill me with Determination!