Nine-Tailed Fox

There are two factors in this story:

1.core

2.cultivation level

The first one is the source of their life and the indicator of their elements which they can use to cultivate.

For example, if Xue has a wood core he is more proficient with wood elements techniques. He can cultivate other elements but his attacks will be far inferior to someone who has that specific element.

And the core has four levels:

1. Ordinary

2. primitive

3. Mutant

4. Sacred

These levels show how far can a person cultivate and use their techniques more proficiently.

The core of a creature cant level up. For example, it cant level up from ordinary to a primitive

The second is the cultivation:

It has only Ascension and Origin for volume 1.

1. Ascension: it has five levels. In this stage, the person would unlock her meridians and learn how to use elements and find their own elements. The first two levels (first and second) will unlock all the meridians and shows with which element you are more proficient. The second two levels (third and fourth) is when you choose your skills and learn how to use your energy. And the last (fifth) is about laying your foundation for the next stage.

2. Origin: it has four levels. The first two are about creating Origin Core and merge it with your own core. The third level is about using your energy outside the body. The fourth level which is the last one is about becoming one with your core.

There is another factor: the soul. Its cultivation level is the same.

Be careful not to get confused. If you have more questions ask in the comments and I will answer ASAP.