Takes place in season 4

When a problem with Twilight's wings becomes too much for Twilight to handle, she would go to the sweetest, most kindest pony she knows to get an answer.

And she did.

But she's having trouble getting the question out and trouble getting an answer. Apparently, Fluttershy is too busy chanting under her breath to bother.

Feathers for the Featherlord doesn't mean what she thinks it means, does it?

Twilight takes the train to Alkzum Mental Asylum to visit her younger brother.

Secrets; every family has them.

Satellite story to Limits of the Horizon

Princess Celestia has faced down gods, and worse, but now she must battle something truly evil. And sticky.

Twilight Sparkle comes across a small, battered diary detailing a new form of transportation. While the research is sloppy and the notes incomplete, Twilight takes it upon herself to see that the ancient project is completed.

Of course, nopony said it would be easy.