This story is a sequel to The Elements of Friendship, Book I: Harmony

After freeing Queen Celestia's sister from the pall of NightMare Moon, Twilight Sparkle has settled down in Ponyville with her new circle of friends. But no sooner does she settle down than a foe from the reign of NightMare Moon returns: Trixie Lulamoon! Bearing a mysterious trinket of great magical power, Trixie leads Twilight to test her assessment of friendship being the greatest magic. What is the Alicorn Amulet? How does it possess such absolute power? Where did Trixie get it from? Who gave it to her, and why? And what was the Sonic Rainboom, and how does it tie Twilight Sparkle to the friends she has just made...?

Can be found on TV Tropes.

The Elements of Friendship, Book I: Harmony
The Elements of Friendship, Book IS [interlude one-point-five]: Bonds
The Elements of Friendship, Book II: Chaoskampf
The Elements of Friendship, Book IIS [interlude two-point-five]
The Elements of Friendship, Book III
The Elements of Friendship, Book IIIS [interlude three-point-five]
The Elements of Friendship, Book IIII

Rainbow Dash was the Iron Wing. She was a war hero, the Slayer of Shadows, the Liberator of the Crystal Empire, the Wrath of Celestia. And depending on who you ask, she still is.

But the war is over. There's little need for a pony like her in peacetime. So she keeps telling herself that she needs to adjust, that she needs to find a new role to fill in the world that she saved. But Equestria seems content to let her remain what she has become, even though they have no need of a warrior.

"This isn't how it's supposed to be", is something she keeps telling herself. But every time she says it, the only thing she can reply is, "so what should it be?"

One whole year after the close of the war, and Rainbow Dash still doesn't have the answer.

Art by NCMares.

Twilight Sparkle has always been frustrated with Discord. His ability to do anything, with no more effort than a snap of his claw. It shouldn't be possible. His power had to come from somewhere.
Then, one day, Twilight lets slip how she feels. Surprisingly Discord agrees to explain it to her. To give her the secret to all of his powers. If she's willing to pay the price that knowing it all will bring.

Twilight Sparkle, a ward of the crown ever since she accidentally turned her parents into plants, is dispatched by Queen Celestia to the small hamlet of Ponyville; the Unicorn has expressed fear that an eldritch Alicorn of the past will arise there. And when Twilight Sparkle fails to defeat the fiendish NightMare Moon in the two Queens' former palace of Concordia Arbos, the planet is plunged into night on one side and day on the other. With only shards of rock to her name and a band of ponies at her side, she sallies forth to bring back the Sun. She will traverse field and mountain, desert and labyrinth if she needs to. Will she be able to solve the mystery of the Elements of Harmony? Who was NightMare Moon, and what evils come to Equestria apart from her everlasting night? And why does Queen Celestia believe that making friends takes priority over everything else for Twilight...?

Can be found on TV Tropes.
Has a YouTube reading by our own Alchemystudent.

The Elements of Friendship, Book I: Harmony
The Elements of Friendship, Book IS [interlude one-point-five]: Bonds
The Elements of Friendship, Book II: Chaoskampf
The Elements of Friendship, Book IIS [interlude two-point-five]
The Elements of Friendship, Book III
The Elements of Friendship, Book IIIS [interlude three-point-five]
The Elements of Friendship, Book IIII

Daring Do is on a quest to recover the Ruby of Raksamakesh! As always, she's prepared for every situation she could think of as she approaches the labyrinth where it is located. That doesn't help when she comes up across something she couldn't have expected; a monster who's...slightly more inept than what she's used to.

Garble has won the Gauntlet of Fire and taken the Bloodstone Scepter. Upon hearing of this, Celestia, determined to stop the bloodthirsty Dragon Lord in his tracks, challenges him to a one-on-one duel for the fate of Equestria and the Dragonlands. An immortal alicorn capable of moving the sun with millennia of experience under her belt versus a teenaged dragon with no experience at all.

Garble accepts.

Stupider things have probably happened, but it's hard to say how.

Cover art is taken from this comic by Niban-Destikim.

Or, Captain Goodguy V Mare-Do-Well: Dawn of Potatoday.

A crossover that nobody asked for.

Part of the Borderworld.

The rain comes falling from the sky. It brings out all the good and bad in the ponies living in Ponyville.

Today is such a rainy day.

Having grown tired of seeing ponies worship the very ground that the Princesses walk on, Discord decides that it's high time ponies started worshiping him instead.

In his very own Cult of Chaos, no less.

When rumors start circulating that Princess Celestia has become pregnant, Twilight is quick to dismiss the rumors as impossible. However, when Celestia confirms the rumors to be true, it becomes quite clear to the Princess of Friendship that something is terribly wrong.

EDIT 7/8/2016: This got featured?! Wow, I am really happy about that!