The Cultivation of a Gu Master

A Gu Master's cultivation is divided into two stages: the mortal one and immortal one. Gu Masters are humans who can open they're aperture by either having the aptitude of by using a special Gu. To advance they nourish the wall of their aperture and break it until reaching the the top of the mortal ranks and then they have the choice of becoming a powerful Gu Immortal via immortal ascension. But whether they ormationinto the immortal ranks or not depends on a lot of factors.

Mortal Gu Masters Cultivation
A Gu Master starts from the mortal realm from rank 1 then they climb their way to rank 5. Each rank is a huge realm and they're divided in inital, middle, upper and peak stage. Up to what realm could a Gu Master reach i s all up to the respective aptitude. To breach through a realm first a Gu Masters nourishes the aperture walls using Primeval Essence up to the highest extent then breaking it to reach a new stage. Each time it is destroyed it means the stage has advanced, or if it means to break through a new rank, the advancement to the next rank. The aperture produces the primeval essence of the same rank and it gets thicker as the Gu Master advances in stages.

Immortal Cultivation
This realm of cultivation is divided into 4 stages, starting from rank 6 up to rank 9. Just like in the mortal realms it requirs time to break through but here the sub realms are invalid and to advance they must pass calamities and tribulations. And because of this they can even have the battle prowess of someone of a higher rank then them, and the level at which they are depends solely on the intentity of said calamities and tribulations. By this train of thought only if a freshly advanced Gu Immortal conqueres and survives 27 earthly calamities and 2 heavenly tribulations than he can be considered at the peak of the 6th realm or rank 6. 