Wang Wei used his ability to see fortune and misfortune to look at the spiritual aura of the lost world to see if there's an immortal cultivator who still lives in this world.
But to his disappointment, there are no immortal cultivators in the lost world. As he already drained all the spiritual aura from the lost world atmosphere and put it into the secret realm.
Wang Wei used his ability and looked at where he laid advanced level formations and his eyes penetrated the timeline of this world and found that one of the loose nascent cultivators broke his formation in search for the spiritual aura.
The intruder searched every corner of the world for spiritual aura and died as his lifespan was exhausted in one of the mortal kingdoms on the main continent. Seeing no anomaly in this world he took back his eyes from the river of time as his sun's energy consumed rapidly upon using this ability.