I just beat this game a few weeks ago.
I got to her three separate times, but I got the game when it first came out and back then, I wasn't smart enough to think of getting higher levels. A few weeks ago, I played through it again, killing every enemy that I could that didn't require struggling to survive which were quite a few of them and I got to level 27-29 or something like that with every brother. The first time I played the game, I only got to about 17 or somewhere around there. This is a really epic song. Great work.