Plan And Schemes (2).
Alec had dispatched his golems alongside his teammates as backup in case they encountered any members of the Royal Mage Academy, however, that wasn’t his primary motive for sending them out.
Alec was able to communicate freely with all his golems as long as they weren’t too far from him.
So when he sensed something off about the individual claiming to be Lucas, he knew it wasn’t the Lucas because he had been in mental contact with Legion.
And Legion had sent a message to him mentally confirming that he was still with the real Lucas, and that was the moment Alec realized something was amiss, yet, even when questioned, he didn’t reveal how he found out, he only twisted his other findings and explained, that way keeping his secret safe.
Explaining how he had discerned that Luis was an imposter would expose another of his abilities—the fact that he could communicate with his golems.