You have to be very, very quick in taking out all of the wizards. I had to jump on a horse and kill all of them using mounted attacks then hurried to the next to get Zhen Ji. Oh, and don't kill the purple emo guy instead of killing the wizards, it doesn't work. The emo guy is the one that summons the Cao Pi clone, which you must kill to obtain Zhen Ji.
And when I say you have to meet the requirements and finish this level fast, I mean you have to do it really, really fast. Be sure to nail the base guard stationed at the enemy producer that Zhen Ji will have to walk past. She refuses to be smart enough to walk north to the clone event if there are any enemies in her way. I did this as I passed that general area on my way to the next wizard. Oh, and do not kill anyone, enemy or officer, that is not required to end the level, required to start the clone event, or required to get Zhen Ji to move her AI's dumb ass to the correct spot.