Note 1: This is NOT a list of character skills, just a list of xianxia terms in Grandmaster of Demonic Cultivation (GDC) aka Mo Dao Zu Shi (MDZS) that are likely to come up in tags, so I might as well give a brief explanation of them.
Note 2: This is by no means a full list of what goes on in canon, just a primer I slapped together from reading the GDC book-- the novels published by Seven Seas have glossaries at the back-- and other xianxia novels and comics, and a bit of extra research to fill in some gaps. There are people who have done even deeper dives into the genre, like whoever runs the Immortal Mountain site. If I made a mistake somewhere or the official translations contradict anything I've already written, I'll make the necessary edits.
Note 3: I'm a Southeast Asian of Chinese descent living in a Southeast Asian country with close historical and cultural ties to China. Some of the Chinese culture prevalent in this region has changed over time and distance, but the roots are still the same, so I try to write what knowledge I do have in ways I understand them to make them more accessible.
Also known as a jindan, it's a golden orb that sits in either the belly or the solar plexus (GDC's live action puts it in the former, and the animation puts it in the latter). It's the crystallization of qi in one's body and acts like the beating heart of a cultivator's qi system, storing qi and sending it through the body at the cultivator's will. Golden cores are always accompanied by meridians, which are pathways that deliver qi from the core to various parts of the body, and three dantian, which are extra energy centers that refine qi for specific uses.
The strength of a golden core determines the strength of the cultivator, and there are many factors that go into determining the core's strength, such as how long the cultivator has been training and the techniques they use, but it also depends on the individual's talent. Most cultivators agree that a person has to start early in order to have a decent golden core in adulthood-- and when they mean "early", they mean as a child. It's as if one's physical growth has a massive impact on the development of the golden core. If someone starts as an older teen or an adult, they don't accumulate as much qi and end up being a mediocre cultivator, or they just don't form a core at all. There have been cases where late starters managed to cultivate powerful cores, though they don't look as youthful as their peers who started younger.
The golden core is typically not affected by anything that happens to the cultivator's body outside of specialized techniques, which is a boon because of the action-packed nature of xianxia fiction. However, if it's gone then it's gone, and the cultivator either dies from the shock (techniques that affect it are often extremely violent), or becomes a mundane human again. For its part, GDC goes further than just saying "it's the center of qi" and really treats it like an organ-- it can be transplanted into someone else if the doctor is really good, though the chances of the donor and receiver dying are 50/50.
golden core
The strength of a golden core determines the strength of the cultivator, and there are many factors that go into determining the core's strength, such as how long the cultivator has been training and the techniques they use, but it also depends on the individual's talent. Most cultivators agree that a person has to start early in order to have a decent golden core in adulthood-- and when they mean "early", they mean as a child. It's as if one's physical growth has a massive impact on the development of the golden core. If someone starts as an older teen or an adult, they don't accumulate as much qi and end up being a mediocre cultivator, or they just don't form a core at all. There have been cases where late starters managed to cultivate powerful cores, though they don't look as youthful as their peers who started younger.
The golden core is typically not affected by anything that happens to the cultivator's body outside of specialized techniques, which is a boon because of the action-packed nature of xianxia fiction. However, if it's gone then it's gone, and the cultivator either dies from the shock (techniques that affect it are often extremely violent), or becomes a mundane human again. For its part, GDC goes further than just saying "it's the center of qi" and really treats it like an organ-- it can be transplanted into someone else if the doctor is really good, though the chances of the donor and receiver dying are 50/50.