Same was the case with the guards patrolling outside the mansion.
The potent hypnotic effect of his magic clouded their senses and the old man was able to skitter past them quite easily without any resistance whatsoever.
The old man's hypnotic magic was a formidable tool, one that allowed him to control the minds of others and bend them to his will. He had honed this skill over many years, mastering the art of manipulating others to achieve his own ends.
Several powerful mages had ended up becoming his puppets with lifeless eyes and most of them had eventually ended up in his dungeon that he used for experimentation to further his research in dark arts.
Therefore he was confident that no matter how tight the security at the mansion could be, he would be able to achieve his objective with ease.
From the amount of magic power he was using just to stay undetected, the old man seemed quite determined.