Usage of Internal Energy

It was his first time inscribing the Freezing rune formation, so Yang Shi didn't dare to be negligent. A small error and all of his effort and soul qi will be wasted.

His hands weren't fast at all. In fact, they were moving very slow.

  The reason Yang Shi was able to inscribe the Burning Petal Rune formation was that he had seen Lin Ying inscribing it before he did.

But for the Freezing rune formation, he only has theoretical knowledge. So each rune he is inscribing was drawn with utmost focus.

The Freezing rune formation was different from the Burning Petals rune formation. The properties of elements, the runic diagrams, all are different.

After one hour passed, Yang Shi's soul qi was almost depleted. But he finished the Freezing rune formation before the soul qi finished completely.