Herbology?
It was a difficult choice to make. Unlike with potion and pill making, he couldn't just casually meld the completely separate practices together, at least not without spending a ridiculous amount of effort and time creating an entirely new path.
This would be something that Ryu would be willing to do as he wasn't afraid of a difficult task. But the question was whether or not it would be worth it, and he wasn't 100% certain of that.
As much as Feng Shui spoke to him, it really was too difficult to find naturally occurring regions of such quality, and even rarer if you needed a very specific kind.
In order to succeed, Ryu would need locations that were absolutely perfect as he refused to take in any Heavenly Favor that wasn't at the pinnacle. However, the shackles of the Feng Shui method were far too heavy.