After Lei Hongji left, Mo Wuji didn't simply stay there; he also left swiftly. He had heard that the person who obtained the Red Karmic Fire Lotus was a Grand Zhi Immortal, and one from Blade Scar Mountain at that.
Mo Wuji had always been enemies with Blade Scar Mountain. Moreover, when the treasure was as precious as the Red Karmic Fire Lotus, there was no need to talk about how it was in the hands of someone from Blade Scar Mountain. Even if it was with someone from the Very High Heavens, Mo Wuji could not give up any opportunity to snatch it.
Since the Red Karmic Fire Lotus was a fire type treasure, Mo Wuji even resorted to wielding his Scholar's Heart on his wrist. The Scholar's Heart was currently a Grade 7 immortal flame, which made it especially sensitive to fire type treasures. The moment the Red Karmic Fire appears, even if it was being hidden, the Scholar's Heart would be able to faintly detect it.