C198 Continuous Variation
Xia Ling had observed earlier that each monster had a different mutation, so there was no value in reference. In other words, Su Anshan didn't know if the people who came out were the same people who went in before.
Since Xia Ling also had this poison in his body right now, he could also mutate it. Why not just impersonate it?
This was equivalent to staying in Su Anshan with a legal identity