Lu Ming had a feeling that he could kill a one-star Celestial Emperor with just the world Energy and the Dominator's Dao without using his physical body.
One had to know that he was only a one star great emperor. If he could kill a one star heavenly Emperor, it would be equivalent to crossing an entire major realm to kill the enemy.
For it to happen to a great emperor or heavenly Emperor, it was an unbelievable thing.
The higher one's cultivation level was, the harder it was to fight those of higher cultivation levels.
To be able to cultivate to the heavenly Emperor realm, which one of them wasn't a peerless genius?
Only by mastering an ultimate Maxim could one cultivate to the heavenly Emperor realm.
Therefore, towards the end, it was extremely, extremely difficult to cross a minor realm to fight an enemy.
Not to mention crossing a major realm to kill an enemy.
Moreover, this was only Lu Ming's estimation.