Only the power of the soul of a Celestial Master could barely catch a glimpse, and even that was just a glance.
After Ji Yongzhao comprehended this method, he didn't have absolute confidence in success, so he made numerous preparations. He arranged for Wei He, the head of the Inner Bureau, to deal with the court dynamics, planned matters posthumously, and planted 'dark players' within the court and certain factions to ensure that he could maintain control regardless of success or failure.
Finally.
He took that step and eventually woke up successfully!
Before Chen Mu, the Da Xuan Dynasty had produced nine Qiankun Grandmasters. The ninth Qiankun Grandmaster died and dissipated after failing to breakthrough to the Blood Exchange Realm before Chen Mu rose in Yu State — but that was merely the surface.