See you underground!

The third elder looked at Sylvan Pembroke with horror in his eyes!
Although some people had speculated this before, it was still so shocking to know that Sylvan Pembroke was an immortal cultivator!
Immortal cultivators...
But it is said that this existence has not appeared in nearly five hundred years!
etc!
The third elder suddenly thought of something. They felt something strange when they were investigating Sylvan Pembroke information before.
How did Sylvan Pembroke, who...