Puppet?

Law Pills, and a type that could permanently increase one's comprehension of the Laws of Light. Not only that, but only Roan knows how to make them. There are other Law Pills out there, but they have only a temporary effect, and their effectiveness diminishes when you consume more of them. At some point, they become ineffective. That shows just how heaven defying Roan's achievements were.

"Roan will never pass on the recipe for those pills. And to be honest, even if he did, no one other than him could concoct them due to the type of equipment necessary for their creation," Rean said. "If I use it as a bargain, I highly doubt the Holamenor Clan would select to give up putting their hands on this pill in the future."