Chapter 143: They Came, They Saw, and They Want To Conquer pt. 4

The crystal is not easy to make because it requires precision and effort. This is why only those who are worthy are given one. A single crystal holds hundreds of souls, reaped and harvested from humans and spirits, which are the fuel to use magic. Wasting it is out of the question… More so, if there are two crystals involved.

Farren doesn't need one because he's originally a demon and magic for him is natural. But because of the current restrictions, his potential is sealed. He can use magic but only to the minimum and that is the reason why he uses a magic crystal. 

Farren saw the annoyance in his master's face and gasped, "M-master! I apologize! Please punish me!" 

He then proceeded to grovel on the ground but his face was showing the opposite. He actually felt happy upon the thought of being punished.

Because he is an absolute fvcking M.