The Final Stages Of The Era Of Conquest.

To be fair, she had been watching Legion ever since the Unified Skill Index, so they couldn't have hidden from her completely. Especially not when she is the keeper of secrets. 

Even the first sage didn't notice her gaze. She doesn't have the power of the dragon king, but she is better than the dragon king at subterfuge. 

She is not as conniving and, frankly, not as powerful as the first sage, but there's a glaring area in which she beat him. She already knew most of what there was to know about Legion long before the first sage dragged them into the illusion.