That was the most basic method of attack. Chen Mu was like a starving wolf who'd seen some delicious food. His eyes were giving off a hot glow, which was very different from his normally calm, cool look. Looking on, Lu Xiaoru was a mess thinking there was something wrong with her card.
The Sound Beam was a powerful card, though its attack style was pretty singular, as he had determined from its principles. Chen Mu guessed there were two places that formed the crux of the sound beam card. One of them would be to use perception to strum the two energy reeds. That looked like a simple strumming, though it must have contained quite a few variations. The other critical place would then be the shape, size and thickness of the energy reeds and so forth.
But, Chen Mu was a complete layman with regard to the likes of musical rules. Even if he understood the crux of those, he wouldn't have any way to deduce the variations among them.