To be, it looked like Twilight was nerfed in that episode, I mean, in first episode where Twilight show her power, she lift 50 tons Ursa Minor and levitated it to everfree forest, but in this episode levitating many animals at once cause her to sweat, not to mention that she sweat and get tired really fast in that magic duel, I just fell that as much as it was really good episode, they made Twilight far weaker then she should be, that is why line " age spell is only for highest level Unicorns " bugs me, there is no way after so many years of training under Celestia, Twilight would be unable to perform spell what she performed when she went overload as filly.