Gravis looked at a dark cave below him as he floated in the sky. The cave seemingly led into nothingness. Not even his Spirit Sense could truly enter it.
This cave led to the Law Comprehension Area for the Law of Humility. Although, it couldn't really be described as a Law Comprehension Area. It was a Heaven's Trial, after all.
However, the concept of a Heaven's Trial included more things than only a trial that killed the weakest Cultivators.
For example, Heaven's Trials could also be set up to teach Cultivators specific Laws by manipulating the world around them.
Physical Laws like the Elements, Life, Matter, and so on could easily be reflected upon physical reality. Creating Law Comprehension Areas for these Laws wasn't really hard.
Yet, how would one teach someone something as elusive as Humility?
How would one even create a Law Comprehension Area for that?