I play VIDEO GAMES! Most of the videos I make go up on a different channel known as Feng Shui Friends. So if you want to see more videos of mine, go there. Each of my videos has a number in the title. If you notice huge chunks of videos missing as a result, they were videos that I removed either for copyright reasons, or because they didn't stand up to my quality standards.
The first battle theme plays when you fight him for the first time and each time he pops out of the background. The second battle theme plays during the final fight of the chapter (if I'm not mistaken).
Fun fact, it was intended in the original for doopliss to have 2 tracks but they ran out of time. The reference to a track still exists in the original code but it's unused and the track doesn't exist so even if you added it wouldn't do anything.