To be honest, you really can't lay a hand on her. Even knowing she's an extremely malevolent witch, you can't do it. The reason is simple: even if you know she's not Zhao'er, you still can't bring yourself to harm Zhao'er's body.
"I, I can't do it, you do it."
You turn your head.
"Sir!" Nicole shouts.
"I know, but I just can't do it." You suddenly turn around.
"Sir, if you don't kill her, she'll come back and kill us. You can restart the game, but we can't. Once we're gone, it's really over!"
"But how can you expect me to do it..."
"Roar!" Outside the tower, a giant roar of the Bone Dragon immediately rings out. Through the window, you see that the bones of the Bone Dragon have turned black, and its body is shrouded in a faint mist.
"Master, the Bone Dragon has become demonic! Kill her quickly, or we're all doomed!"
"But..."