Luo Feng didn't kill any of the universe masters captured.
He knew clearly that even if he killed them, there would be universe-masters-to-be who would become universe masters in no time. Purple Moon Holy Land was far younger than Eastern Emperor Holy Land and didn't have that many universe-masters-to-be, but it could definitely have eight to ten more universe masters, so Purple Moon Holy Land wouldn't be affected at all. He figured he might as well just keep them as leverage against Purple Moon Holy Land.
"It's only a pair of wings, so it's only an ordinary true treasure to Purple Moon Holy Land. I can't believe your ancestor isn't even willing to trade it for four universe masters." Luo Feng shook his head and exclaimed. "He's ruthless, too ruthless! He doesn't even care about you."
All four universe masters were enraged.