For example, in the battlefield of the illusionary Emperor, two illusionary emperors would enter and kill each other.
Firstly, he could train himself. Secondly, he could kill his opponents and weaken them. He could also obtain rewards.
In the heaven realm, the rules were that if one hunted alien races and took their crystal cores, they would be rewarded.
There were also corresponding rewards for the alien races. Killing the heaven realm's powerhouses would also give them rewards.
The battlefield of true emperors was a battle between true emperors.
It was the same for the battlefield of great emperors!
Moreover, for so many years, there had been an unspoken rule between the two sides that true Emperor powerhouses were not allowed to enter the battlefield of the empty emperors.
Great emperor experts couldn't enter the battlefield of true emperors.