ha! I knew it was you the instant I saw the sketch xD *nods in approval* glad you take suggestions. Ponies invading the U.S. xD "RUN! IT'S GO-ZILLA!" level of epicness xD how they got here from Ponyville? da hell knows IT'S MAGIC! they don't got explain nothin'! (specially when each is easily 50 stories high)
Idk why but these sketches are so much fun when you make them xD Trixie and Twi seem like the best of rivals lol (well DUH)
Twilight probably would only go for "just enough", though. Too modest to use her full potential if she doesn't have to, and she would probably try to limit the collateral damage... Plus, she probably doesn't want to HURT Trixie, just knock some sense into her.
Of course, despite her massive potential and incredible knowledge, she's probably not very experienced in this kind of magic. She just might lose focus, and have the growth spell go out of control~