A Mysterious Ancient Fortress
"I never met any higher monster than those weaklings down below," she said before flapping her wings for a minute and landed on the ground, just half a mile away from the hill. "See? There is the fortress," she turned into human form and pointed towards one side of the hill.
There was a collapsed line that was covered in dirt. Behind it Arthur could see a wide deep gap, with darkness prevailing there and no light to see anything.
"It's like a destroyed rudimentary stronghold," he muttered.
"Try to sense its energy then."
When Arthur tried to spread his cultivation energy to that stronghold, he felt a strong resistance coming from inside, and some pain. "Damn, it's really strong," he held his head for a moment as he felt like a sharp long thorn just touched his mind dantian, making him feel a moment of excruciating headache.