Her little beasties hated Nalan Lan to the core as well. Ever since the Dong Chen Kingdom, she had plotted against Sima You Yue many times, it was just that they had managed to escape.
It went without saying that Nalana Lan's luck was always full to bursting and was always able to escape.
This time, she had come again and Sima You Yue had no plans to let her off. In order to stop her from escaping using some unknown method, she immediately opened her domain the moment she came. Unless she was able to break through her domain, she would never be able to escape.
However, even if she had a lot of ways to escape, she wouldn't be able to break through the domain. This was why SIma You Yue relaxed and watched as her beasties would deal with her.