"Coincidentally attacked Yan Xiu?" Fang Zhengzhi was unsure of what went through Monster Emperor Baizhi's mind. However, he was sure that if Monster Emperor Baizhi wanted to kill Yan Xiu, there could only be two outcomes.
Firstly, Fang Zhengzhi blocked the attack of Monster Emperor Baizhi for Yan Xiu. In this case, Monster Emperor Baizhi's power is depleted. Fang Zhengzhi suffers grave injuries while Yan Xiu remains alive.
Secondly, Monster Emperor Baizhi blocks Fang Zhengzhi with her body to stop him from rescuing Yan Xiu, which was equivalent to forcefully blocking Fang Zhengzhi's attack. In this case, although Yan Xiu will die, the infuriated Fang Zhengzhi would definitely be able to trap Monster Emperor Baizhi successfully.
These two outcomes…
Regardless of which, it requires time.
Whereas if Monster Emperor Baizhi decides to give up on killing Yan Xiu, she could get away with the most amount of time without consuming any energy.