Talk:Episodes, films, and shorts/@comment-26973802-20140508012959/@comment-26973802-20140508195251

This was presumably before they had the Elements of Harmony. If they used the Elements on Tirek it would either destroy him or turn him to stone. Nightmare Moon was only banished because Celestia didn't possess the full power without Luna. They probably just used their own magic like they did with Sombra.