The moment the three Titanium Guards were destroyed, Hao Ren instantly felt that something was amiss.
This was due to their opponents' complete non-reaction.
Hao Ren was dead sure that the three Titanium Guards did not respond. It was not that they could not react on time. Vivian, Y'zaks and his attacks were quick for sure, but they were not so fast to the point that they could beat the physical distance between them and the guards. Y'zaks' demonic flare took at least a tenth of a second to reach the enemy, and in that split second, even if the three guards did not manage to dodge or counter-attack, they would have at least displayed some reactions.
Hao Ren felt that he had hit a stationary target, which did not have the tiniest reaction.
Hao Ren was not the only one to think so; Vivian and Y'zaks, who were experienced fighters, had also noticed the anomaly. Y'zaks leaned down and said, "Something's not right."