It was enough for him to experiment.
After using another reward, Lu Yi suddenly felt a vast amount of insight about the Sky Tunneling Technique emerge in his mind.
He absorbed these insights at an extremely fast rate, and Lu Yi discovered that his speed of comprehension had more than doubled compared to before.
Indeed!
Lu Yi's eyes lit up; the effects could be stacked.
Lu Yi continued to comprehend.
Four months later, Lu Yi had absorbed all the insights, and his Sky Tunneling Technique had improved to Level 5.
Lu Yi didn't stop there and decided to use the other two rewards that each added +4 to an Immortal Skill Level as well.
This time, it took him half a year to absorb the insights, and the Sky Tunneling Technique was raised to Level 9.
Only one level away from the limit, Lu Yi checked and found that he still had two rewards left that could add +3 to an Immortal Skill Level.
He hesitated for a moment but ultimately chose to use them.
