In this stage, cultivators have to condense their liquid Qi sphere in their Dantian into a solid core. Upon success, their lifespans are increased by hundreds of years, up to 500 years at the late stages of Core Formation. Cultivators of this stage can also refine magical treasures using their core fire. By entering this cultivation stage, most cultivators can enter as high-level disciples or even elders, depending on the size of a sect. If not, most can travel freely throughout the world as vagrant cultivators with relative ease. The bodies of Core Formation cultivators are also strengthened as marrows are washed and cleaned of impurities.
An individual enters the Core Formation stage when they collect and further condense their spiritual energy into a solid "core" - often depicted as an Orb. At this stage individuals increase the lifespan of their mortal bodies by hundreds of years, and have greater power that dwarfs Late Foundation Establishment cultivators.: "The magic battle between the core formation cultivators of Saber Transformation Dock and the Controlling Spirit Sect had shattered the heavensand earth and swept back and forth over several kilometers."
Cultivators at this stage are considered elders within middle level sects, and are often used as a measurement of strength between Sects. Loss of a sect's Core Formation cultivator represents a major loss in a sect's strength.
Within the Core Formation level there is again 3 groups - Early, Middle, and Late Core Formation cultivators. The difference between the three groups is larger with a Late Core Formation cultivator being able to effortlessly kill many Early and Middle Core Formation cultivators. Progression through Core Formation involves absorbing even greater amounts of spiritual energy and making their "core" even denser. The power of the "core" and the way strength is gauged in this stage changes over time.
Early Core Formation
This is the initial cultivation level upon entering Core Formation. Those of this stage can easily kill Foundation Establishment cultivators.
Middle Core Formation
By continuing to further condense their now solid core in the Dantian, cultivators can advance their strength by leaps and bounds, making it that most Middle Core Formation cultivators can beat Early stage ones.
Late Core Formation
Further condensation grants even greater strength, with Late Core Formation cultivators easily beating most cultivators of a lower stage.
Sub-Stage: False-Nascent Stage
Also known as Peak Core Formation cultivators, they have reached sufficient density whereupon the core can be called into a collapse, initiating the Nascent Soul stage. Almost always capable of easily beating other Core Formation cultivators of a lower stage.