Animale is a legalized drug that provides users temporary body modifications - have your own unicorn horn, ears, wings, for a night. Not to be abused. Ever.
The Kiss of the Alicorn is a spell. It can only be cast by an alicorn, and only a single time. It allows them to share their immortality with one other pony, so that they don't have to face eternity alone.
Luna has spent untold lifetimes in the dream world with other ponies, and on a cold winter night, she settles in for another- with a colt who has just one hour to live.
Eternity is something that can never be reached. Even Equestria's princesses won't live forever. The end, however, comes much sooner than anypony expected.
Every day, Princess Celestia wakes up in terrible pain, and every day, she chooses to endure it, until the one day she's left feeling blissfully normal. Few things have ever scared her so much.
Celestia is the very image of beauty and perfection, and has been for over a thousand years. Inevitably, she receives a large number of letters every Hearts and Hooves Day. Luna is not amused, especially when they interfere with politics.
Apple Bloom wants to see her parents, the Cutie Mark Crusaders want their cutie marks, so they do the the only logical thing and try to raise the dead.
Twilight wakes up one day to find that things are different. Everypony is gone, and there's a persistent sheet of fog dominating all of Ponyville. But that's the least of her worries. It only escalates from there.
Twilight has to learn control now that she's an alicorn. Princess Celestia and Luna refer her to an old book that should help her learn, but what she finds in there will not leave her mind.
Cadance starts a paid dating service, doubling as a firm for marriage and divorce law, and hires a 'reformed' Chrysalis as an intern. Nopony's relationship is safe.
Extreme long-range teleportation is fraught with frequently-unexpected complications. Twilight and Celestia find themselves caught within one such complication for an entire week.
Twilight Sparkle failed her entrance exams for Celestia’s school. Worse, she is a danger to both herself and others, resulting in her magic being suppressed. Dreams crushed and now one of the weakest unicorns, a nightmare comes to her.
Congratulations, Twilight. With the Princesses on vacation, you're in charge of Equestria. Perhaps it's a bit early to congratulate you. After all, whether it's a jealous nobility or an unhappy military, your reign will be anything but
Preparations halt when Princess Celestia forbids the playing of the Equestrian national anthem at a concert after a copy of its original is discovered to still exist. Despite her warnings, Octavia Melody endeavors to uncover the truth.