Twilight finds a spell while in the Castle of the Royal Pony Sisters. She tests it on Starlight Glimmer, with sexual results.

Twilight normally would not use this spell, as what her friends would think. But this was what she was waiting for.

Starlight is just a few words away for trance. Starlight is a few words away from having sex.

"Starlight, Focus and Obey. "

"I will obey, my Mistress."