The Mandarin Duck Mirror, Wang Chen had mastered it far too well.
He himself possessed two sets of Mandarin Duck Mirrors, one of which was the highly advanced Ten-hour Mirror, capable of maintaining its effect for ten hours once activated.
In the past, when Wang Chen was excavating secret passages, he would set up Mandarin Duck Mirrors to keep track of the situation above ground.
Therefore, he was extremely familiar with the characteristics of the Mandarin Duck Mirrors.
Upon searching this mine tunnel previously, Wang Chen felt as though he was being watched.
Although this feeling was very faint and he could not pinpoint its source, he was certain that it was not an illusion.
Wang Chen was very confident and trusting in his own perception abilities.
But at that time, he did not investigate the source; instead, he had completed the search of the entire mine tunnel and then made a surprise return attack.