"Refining the Eyes of the Netherworld is quite simple. You just need to drop a droplet of your essence blood on the Heart of the Netherworld, and then refine it according to the technique I give you!" Qi Luyi then passed a set of refining techniques to Lin Feng.
Lin Feng immediately memorized the techniques and slowly practiced them, seeking Qi Luyi's guidance whenever he encountered anything unclear, who would then elucidate each of Lin Feng's queries. By the time Lin Feng had grasped the techniques rather well, Qi Luyi also informed him of some precautions and handy tricks to use during the refining process.
After Lin Feng had fully mastered the techniques, about five to six hours had already passed.