Who is Princess Luna's sister?

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Tags

1. #transformed
2. #circumstances
3. #little
4. #season
5. #celestia
6. #known
7. #alicorn
8. #under
9. #princess
10. #premiere
11. #friendship
12. #certain
13. #nightmare
14. #antagonist
15. #other
16. #sister
17. #night
18. #magic
19. #younger