Wang Yun feared that Lü Bu might act impulsively and ruin the grand plan, so he held him back and spoke to him privately for a long time. Lü Bu agreed to follow Wang Yun’s instructions to kill Dong Zhuo. 
Lü Bu pretended to be remorseful, showing regret and not daring to confront Dong Zhuo again. Dong Zhuo, seeing that Lü Bu was still loyal and protective, forgave him and allowed him to stay by his side as usual.
One day, Dong Zhuo brought Lü Bu into the court. Wang Yun, with a group of loyal ministers, secretly prepared a large number of soldiers. As soon as Dong Zhuo entered the palace gates, the ambush soldiers attacked him with long spears. However, Dong Zhuo was wearing armor and was not killed immediately. 
Dong Zhuo cried out, ‘Lü Bu, save me!’ Lü Bu, brandishing his halberd, shouted loudly, ‘Lü Bu serves the Emperor and will not tolerate a traitor like you, Dong Zhuo!’ With that, he thrust his halberd towards Dong Zhuo, killing him.