Inside the underground chamber in Iron Demon City,
Currently, Ace was practicing his rune crafting while trying to achieve tier-4, and he was very close to drawing the lightning symbol when suddenly the symbol suddenly turned into dark light particles as Ace's focus suddenly snapped.
Ace was startled first before his heart palpitated when his soul sense buzzed in alarm. However, he didn't use his heavenly sense because this danger wasn't from inside the chamber, but it was from outside.
He looked toward Noa and saw she was completely oblivious to this deadly feeling from outside and felt relief when he thought this was probably because of this room's special material that they remain out of mischief.
Ace finally lose his nerve when he thought they were still safe inside here and might not suffer any danger as long as they wait until this danger passed.