It was during the time his dungeon was breached by a coalition of adventurers led by the guild named Seven Swords Guild. Simon had just completed the fourth trial in the forbidden grounds and had arrived in his dungeon, only to get that news.
Of course, their attempt was met with a failure, as Simon did not spare anyone and wiped all of them out or took them as convicts to be questioned and later killed except for one, that guy managed to escape.
There was one person among the lot who had intruded his dungeon pretending to be under the coercion of the Sea God's Guild and observed the entire spectacle while hiding as Simon wiped out their entire party.
That guy who called himself Bryan or 007 a senior executive of some organisation called as Cerberus was able to hide from the surveillance of the dungeon. Assuming that it was a skill that was developed by the Adventurer's Association to tackle the dungeons as said by Davis Hall, that guy also possessed another peculiar ability.
