Gu Xue had said so, and Luo Yang had no reason to press her further.
Asking more would be pointless since she insisted she had no connection to Skull Fortress, which would only waste his breath.
Having not known the three Gu sisters for long and lacking deep understanding of them, Luo Yang could only remain on guard. If he discovered any unusual actions from them, then he'd settle accounts with them accordingly.
"Wife, then make a vow," Luo Yang demanded.
"Eh, what use is a vow?"
Gu Xue pivoted the topic, asking about the treatment for her Yin Spirit injury.
"Eh, when will you fix my wounds?"
Back then, he had asked Hua XiYi about it, but she had conditions—she would only disclose how to heal a Yin Spirit injured by the Soul Destroying Nail if she were given the Blood Devil.
Whether the Blood Devil could even be located was still an unknown.
As for when precisely the Soul Destroying Nail could be extracted from Gu Xue's body, Luo Yang wasn't certain either.