A metaphysical condensed energy crystallization of spirit power or bloodline essence indicating the advancement of one's martial soul comprehension or one's bloodline's evolution to a higher life stage as well as cultivation foundation. Depending on the source from when a soul core is condensed, the possessor's potential is permanently amplified on the path of that source and the affinity is increased to that source. A soul core functions as a storage collecting unit, allowing the possessor to lessen the rate of loss: recovery of its source. Soul cores can also be voluntarily controlled by their possessors. The soul core can be condensed within living beings by their own cultivation progress. However, there are different types of soul cores, depending on the method used to condense it. Such are standard soul cores that follow the basic rules of soul core formation, as well as divine cores and bloodline cores that exist outside these rules.
A soul core was a synonym for a high level Spirit Master. In general, the solidification would only succeed when one reaches the realm of seven Spirit Rings. As the core of one’s Spirit Power, it would get rid of the old to bring in the new and it would allow the Spirit Master’s combat strength to increase substantially.
The concept of soul cores pre-date mortal humans, existing since the era of the Dragon God and his Douluo Divine Realm as natural cores derived from Divine Beast bloodline essence and Divine Cores of true Gods. Such knowledge was pass down to his Dragon Clan spirit beasts, such as Di Tian, and instinctively to all spirit beasts. Over time, as human spirit masters advanced their cultivation ranks, they encountered the circumstances of soul core condensation after becoming Titled Douluos, allowing advancement in their comprehension and cultivation.
The standard information of a soul core was not widely spread in the cultivation circle until Huo Yuhao's era. At the time, the most knowledgeable of soul cores was Di Tian except the Gods of the Divine Realm.
Before Yuhao's era, mortal human Titled Douluo powerhouses condensed soul cores after becoming Titled Douluos through their higher spiritual power and higher physique, as exhibited in the Spirit Ranks of Soul Land and Soul Land II concerning Quasigod Douluos. With the later era's widespread information about soul cores as well as the rise of spiritual power and physique level necessary to contract Spirit Souls, eventually human cultivation ranks at Rank 70+ and Rank 90+ changed to reflect this, as seen in Soul Land III and Soul Land IV.
By Tang Wulin's era, mortal human cultivators have standardized soul core knowledge into cultivation practice, with the condensing of a soul core after attaining Spirit Sage rank as a mark to become a Titled Douluo, a later second soul core after attaining Hyper Douluo rank to mark a potential Limit Douluo and a third soul core at Limit Douluo rank to mark a potential mortal God. Each new soul core may fuse with previous ones or affect them because of the instinct to evolve into a Divine Core.
The common method human cultivators use to form their subsequent soul core is through the resonance technique.