It's true that Twilight is far superior in terms of sheer magical strength, but illusions can still have a profound effect on their target. I know it would never be in the show, but I picture the two having a magical duel.The mental image that I get is pretty awesome lol, I picture Trixie rolling to the side as she dodges a spell, casting her own. All of a sudden an image of a VERY angry Celestia towers over Twilight and is all "TWILIGHT SPARKLE!" like in Lesson Zero, and Twilight is basically rendered useless as she freaks out.Heh... just how I pictured it lol