From the Source

Extreme Realm, Emperor's Son, Taboo

The realm that all sentient beings cultivate is a normal realm. There are always people with extraordinary talents who can cultivate a realm to the extreme. This is the ultimate realm. Those who are in the extreme state are the proud ones of heaven. There are those who are in the extreme state, and there are naturally those who can break the extreme state. Anyone who breaks through the extreme realm is a son of the emperor, a son of an era.