During the final battle against King Sombra, Princess Luna takes the battlefield with her sister as well as Taurus, Aries, Pisces, Aquarius, Leo, Libra, Virgo, Cancer, Scorpio, Gemini, Capricorn, and Sagittarius, the most powerful ponies of their generation.

And, although Sombra is defeated, a new addition to the sky will remind Equestria of their losses for millennia.