When Oliver appeared, the member of the assassin's society immediately became alert. It was not the first time that he was faced with a character of his caliber and he knew that he could not defeat him, however, he was not scared, because he was confident of escaping.
He only thought this because he didn't know that if Andrew didn't want him to leave this place, he had no way of doing it. The man immediately analyzed Oliver's strengths and was sure that he was a peak-level senior expert or a super expert.
If Oliver was the first, there was no problem because he was 100% confident of losing it, but if he was a super expert, the situation was a little more complex. He still had confidence in escaping, but he would have to use some tricks.