You'll Play Your Part is the sixteenth song of season four of My Little Pony Friendship is Magic, featured in the twenty-fifth episode Twilight's Kingdom - Part 1. Part of the song was first revealed in a preview on TVGuide.com during the week leading up to the episode's premiere. In this song, Twilight Sparkle doubts her role as princess, but Princesses Celestia, Luna, and Cadance assure her that she has a role to play. Princess Luna sings her first solo during this song. An instrumental version of the song is used in the last three levels of Hasbro's online game Key Crusaders.