Fifteen days went by in the blink of an eye.
During those 15 days, Chen Mu put all of his attention on deepening his understanding of the two cards in his hands. That wasn't much time, but he still got obvious results. He didn't know if it was because he had more insight or because his ability to control his perception had gotten stronger, or because of the two combined, but he gained a lot during those 15 days.
He mostly focused on the Bipolar Thunderball and the Snake Lens. His messed up experience with the Golden Word Shackle had scared him away.
Since the Snake Lens included a legacy fantasy card, that made studying it a lot easier. Since there wasn't much time, though, he had only just begun to understand a little about it. If he wanted to really master it, he would need more time.