C115 Refining True Spirit Marrow

"The temperature of the furnace is indeed low, and it's too difficult to control. Furthermore, it is still ordinary charcoal, and there are a lot of impurities in it …"

"I don't dare to use too much strength on the chopping board either. If I use too much strength, I might even break the chopping board and the ground …"

After saying a few shortcomings in one breath