Zhou Tian's own strength was stronger than those Ancient Powerful Beings, and without them combining their strength, they likely wouldn't have been able to match him.
Given the situation at the time, not to mention the possibility that Zhou Tian could enhance his strength by seizing the treasures of his foes. Even if he couldn't improve his strength in that way, as long as everything in the current battle proceeded smoothly, he would still be able to kill three of the Ancient Powerful Beings.
It may seem like the number of three Ancient Powerful Beings isn't much, but in reality, if Zhou Tian could indeed kill those three, it would have a tremendous impact on the subsequent combat.
After all, although those Ancient Powerful Beings defeated Zhou Tian by numerical superiority, their actual numbers were not large. Moreover, given Zhou Tian's strength, if the number of Ancient Powerful Beings did not meet a certain standard, even their combined strength would not pose a threat to him.
