The Pony of Shadows. For generations, this creature of myth has terrified every pony who heard about it, and it became known as the source of all the darkness, cruelty and wickedness in the world, the wellspring from which evil flowed. Twilight, who has led her friends against many foes in the past, seeks out this ancient enemy of her people, to vanquish it once and for all.

But when she finds it, she and her friends instead discover a different story. One the young Princess would never have expected.