In the Core Formation Realm, one would focus on accumulating Spiritual Qi and move through its minor realms to form their golden core to perfection. But during this process, cultivating the soul should not be neglected, in fact, it might even be more important.
This was due to the fact that the strength of a cultivator’s soul in the Core Formation Realm determines how powerful their Nascent Soul upon entering the Nascent Realm would be. With a strong Nascent Soul comprehending the laws of heaven and earth would be much easier.
Strengthening the soul would result in a cultivator's Spiritual Sense increasing, from this cultivators use this as a measurement of how strong the soul is.
Early Core Formation Realm cultivators' Spiritual Sense would normally be three hundred meters. Mid Core Formation Realm cultivators' Spiritual Sense would be six hundred meters, and cultivators at the Peak of the Core Formation Realm Spiritual Sense would be around nine hundred meters.