Solutions (2)
When Yun Lintian saw this scene, he immediately thought of a laser reflection experiment. Obviously, these stone pillars served as mirrors, reflecting the sword beam.
While he was thinking of this, the Heaven Piercing Sword had already arrived at the third pillar. A similar scene appeared once again, confirming Yun Lintian's guess.
Afterward, the Heaven Piercing Sword repeated the same process one after another until all the ninety-stone pillars were arranged perfectly.
Buzz—
Soon, the first stone pillar released a sword beam, and the beam continued to jump from the second to the third until the last. After that, the sword beam from the last pillar went straight into a wall made of gold at the end of the hall, and a passage was slowly revealed before everyone's eyes.
The Heaven Piercing Sword quickly flew back to Yun Lintian and shook slightly as if it was asking for a compliment.
Yun Lintian touched it and said. "Thank you. You're awesome."