Didn't Do A Proper Research

"How did you do it?" The girl asked a bit hysterical. 

She had been monitoring Grey's movement since Grey stepped into the first room, yet she never sensed it when he altered the array. 

"While we were fighting. I already knew you would sense it if you weren't distracted, so I walked in here as if I was oblivious to it." Grey chuckled, "Since you're an assassin then you should be aware of my profile, right?" 

The girl looked at him, unable to speak. She did read about his profile, but this array was an ancient array she stumbled upon while on a mission. Even her seniors in the Elemental Sovereign Plane were baffled by the array, yet Grey not only managed to sense it quickly, but he could also alter it to his advantage in such a short time. 

"Impossible! Where did you get the array? Speak!" She didn't believe Grey didn't know of the array.