During the boss battle, what am I supposed to do when I knock her down? I've wacked her over 5 times and am a little confused.
Go behind her and hit the butt under the tail. This can take between 5 and 10 hits depending on the difficulty level.
Generally, if you time the knock down properly and have high stamina level when it happens, you can get in between 2 to 4 hits.
Sometimes she gets up faster and you might not be able to get in even a single hit if you're in a bad position during the knock down.