Twilight had never questioned the nature of the Tree of Harmony. To her at least, it stood as a sentinel, a silent guardian watching over Equestria and keeping disharmony at bay.

She soon starts to have questions and misgivings when she inadvertently witnesses the horrifying fate of hers and the rest of her friend's twisted doppelgängers. Did something happen to the Tree of Harmony, or was it always this way?

Twilight aims to resolve this mystery once and for all. Little does she realize that this mystery goes far deeper—the truth far more terrifying than she can imagine.

Will she be able to solve this nightmarish mystery with her sanity intact, or will she surrender and be lost to madness?

After some deliberation I chose to put a Crossover tag as the whole story uses many assets from several stories in the Cthulhu Mythos (most of them written by authors other than Lovecraft).

Fantastic cover art done by Mix-up!

You never know when evil will strike, but you can always be prepared for it. Seeing your heroes become the villains can be a disaster, but like wounds, disasters can heal. However, when heroes became villains once again, they won't fall for the same trick twice.

The Mane 6 once fallen to the dark side after exposing themselves to some water filled with dark magic and almost destroy Ponyville in their madness. They eventually were cured and return to their senses and cleanse the evil waters from its impurity.

However, a small bit of that dark water was saved and was given again to our heroes. With the Mane 6 fallen again to madness, it is up for other heroes must save them once again.

Assuming if they can this time...