Discord is bored.
Side effect of being trapped in stone.
But, that does not mean he's powerless. Quite the contrary.
He often wanders around the universe, if only as a spectator.
Throughout his wanderings, he finds a war-embroiled world, where the Vasari and Ortalians clash for control of Liguria.

Of course, Discord cares not for the conflict. Like a curious magpie, he 'borrows' one of the Ortalian mechs and brings it to Equestria just because.
An accident of sorts occurs when he causes damage to the mech's delicate mainframe, rendering it stupid, to put it simply.
Now, a barely coherent machine of destruction is wandering about on Equestria, fully loaded for war...

Some of you may ask whether or not the Executioner brings about extensive collateral damage to Equestria.

But the real question is whether it can discover the magic of friendship.

Twilight Sparkle is sent to the future and learns how integral she is to the friendship between the rest of the Mane Six.

Note: "Why is there a crossover tag? There doesn't appear to be any crossover going on!" Well, it's not really a crossover, but it could be classified as one. See, I borrowed a plot from Teen Titans and ponified it, and some people would say that's a crossover.

A changeling gets a very risky and clever idea.
Pretending to be an advanced magic doll left as an anonymous gift in front of Twilight Sparkle's home.
It's so audaciously stupid there is no way it's not going to work.

Twilight becomes alicorn of the stars. This is sort of a problem, because Luna kind of already was alicorn of the stars. Oops!

TV Tropes

this is a spin of of a story a co-writer and I are writing Princess Celestia is pressuring her son to get married and he runs away complete with scootalove Caution: if you do not like for the queen to have a large roll this might not be the story for you

A former pink pony finds herself in a new, hostile world and a new friend who's perhaps even more hostile. A small, angry man finds himself with a new friend he didn't want. Can they make it through this new misadventure together, or is it the universe that needs to watch out for them?

Cover art used with permission from Technaro.

This story is a sequel to Lyra's Human

Several years after the events of Lyra's Human, Derpy Hooves decides that she's lonely, and wants to meet a human for herself. Together, Derpy and the human have crazy adventures across worlds as both learn what it means to be true friends.

Story image courtesy Shadow Squirrel