Golden Core金丹
jīndān
A crystallized core of refined qi formed in the dantian; in most power systems, the milestone that separates true cultivators from students.
The golden core borrows directly from Daoist internal alchemy, where jindan names the "elixir" of perfected practice. In fiction it is a literal object: the cultivator compresses years of refined qi inside the dantian until it condenses into a rotating core, unlocking flight, vastly longer life, and spell-like techniques. Many settings grade cores by quality, with a flawless core determining how far the rest of the path can go.
Its cultural footprint is large enough that fans of Mo Dao Zu Shi will know the term from one of that story's most consequential plot points. The next classical stage, dissolving the core to birth a soul-double, is the nascent soul.