1, Zhuge Liang's opening plan
I think Zhuge Liang is a better strategist in the romance of the Three Kingdoms, which may not be thought of by everyone. But I personally think that the empty city plan is one of Zhuge Liang's opening plans. Although he didn't have an army at that time, he could only put down an empty plan to scare Sima Yi. But I personally think he is sure, because if Sima Yi didn't see through the plot, he would be safe.
Even if Sima Yi saw through the plot, Zhuge Liang knew that Sima Yi would not kill himself. Because Cao Pi was very suspicious, after Zhuge Liang's death, Sima Yi was not allowed to lead troops. Zhuge Liang is a great worry to Cao Pi. Now that this great worry has been removed, there is no need for him to cultivate another Zhuge Liang.
2. Pang Tong's conspiracy
We all know the story of burning Chibi, and Pang Tong also knows that Cao Cao doesn't know how to fight water. So pretend to take refuge in Cao Cao and give him advice. Pang Tong suggested that Cao Cao connect the boats together to avoid turbulence. There seems nothing wrong with Cao Cao's suggestion, but it turns out that it is convenient for Pang Tong to set fire to Cao Cao's barracks. This is a conspiracy. This is a pit. Pang Tong dug a hole for Cao Cao to jump in.
To sum up, there are essential differences between conspiracy and conspiracy, and conspiracy is more aboveboard. Let others know that he is a trick and there is no way to crack it. And conspiracy is what we usually call digging a hole to make others jump.