The blow came out of nowhere, judging from the nature of the attack, it was a pure elemental blow and it carries chaos Qi and wind element, even though he didn't saw whom have attacked he is quite confident that it was the cloaked chaos knight.
The only one who was able to bypass his spiritual sense and instinct, just like him the cloaked chaos knight is a being that focuses on spiritual strength.
Fortunately he had increased his grip towards the assassin, if this guy was ever released it would definitely spell big problem for him, the assassin on the other hand was furious.
He had nearly escaped the binding earlier but on the last second, the force that the tails use to bind him increase tremendously, if it weren't for him struggling and his armor being able to endure, his bones would have been broken.