Cognition within the multiverse is merely a casual move by Lu Yuanming. He intends to test whether he can preach across the multiverse, rescuing others while simultaneously accumulating sufficient Wishing Power.
Lu Yuanming admits he cannot save everything; this is the limitation of his existence as a living being. If he were already transcendent, then naturally he would see everything rescued in one glance. Sadly, he is not, so he can only attempt to save what he encounters and sees.
The appearance of these three children proves that his method is feasible.
His cognition is inherently tied to him through causality. Simultaneously, he possesses Absolute Vision, which allows him to perceive any place in any space-time linked by causality. It also means he can aid those connected to him by causality at any moment. This act would attract the favor of The Force, turning those bound by causality into the main characters of their respective worlds.
