Chapter 553
(Unedited)
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While fighting against the Shadow Being, Shin Jiao has started to learn how to use the Essence Syphon technique. He has gained an understanding of its complexity and control. Though it is not yet to the point that he is able to freely wield it with just his thought, but writing its runic value is already possible for him. After using it three times, he has already somehow deduced the effect of the 'Essence Syphon' technique.
With this knowledge coupled with his advancement in rune knowledge, Shin Jiao now has the ability to write its runic value, though not that proficient enough. This is the reason why he has to spend a lot of energy. And of course, the other reason is that he is currently writing down heavenly runes, which are thousands of levels higher than normal runes.
And the thing that he is carving the heavenly rune is a single sharp object.