It was another day at the School of Friendship when something unusual appeared in the sky. Within minutes, it had launched its assault, seemingly destroying everyone it caught. And it left no room to escape. Whatever it did left no survivors.

Except one.

Silverstream was trying to fly as fast as she could with her friends at her side. After watching them dissolve one by one, she turned around in time to see one of those things approach her faster than she could react. She covered her face...

And that's where this story begins.

Technically a mass crossover, but it should be clear what the main crossover is.