The so-called Tribulation of Dao-Transformation is simply the mental and spiritual trial that manifests when a cultivator's cultivation breaks through into the Carefree Realm.
Unlike the inner demon tribulation, which projects actual inner demons into physical form, the Tribulation of Dao-Transformation does not materialize externally. Instead, it quietly invades the Purple Palace to assault the divine soul.
Those with unyielding willpower who encounter the Tribulation of Dao-Transformation will simply be reduced to fools, though they will not lose their lives.
Chapter 266