The technique wasn't overly complex. But, in reality, neither were any of the other ones that Ryu had seen. The techniques of the True Martial World were inherently simple. By their very nature, they made cultivation as straightforward as it gets.
However, even in comparison to others, this was even more simple. Though, just from a glance, Ryu could easily see just how complicated this technique could become.
The essence of the technique wasn't hard to grasp. You cultivated by refining pills. The medicinal fragrance of the pill was used to refine your qi and strengthen your body.
Interestingly enough, the pill never needed to be swallowed. The technique relied on snatching the support the pill refinement process gained from the Heavens to then, in return, refine the body itself.
To the Heavens, the greatest form of "pill" were Spiritual Herbs themselves. This was the "pill" processed and formulated by the Heavens for human consumption.