The Diamond Elf King's overall Cultivation base was ranked quite low among the various Spirit Monster Emperors, and comparatively, his Cultivation base was also a bit lower. Moreover, his fundamental attribute was the earth element, which is the most temperate among all attributes. If it had been the fire attribute, Tang San's current Cultivation base would not have been able to bear such a Bloodline Brand.
Furthermore, the immense life force brought by the Tree Ancestor Brand to nourish his body's origin had made this one month of Cultivation in Jianmu City incredibly crucial for Tang San. It compensated for the previous deficiencies in his body, repaired the injuries sustained during his Tribulation, thereby accumulating an enormous amount of Life Force, and expanded his bodily capacity manyfold.