Why didn't Feng Ran kill Wu Huan?

Does the subject want to ask "Why didn't Tianqi kill Wu Huan"? The first reason is that the power of the apocalypse is not as good as before. After all, he was killed by the white army, and he was resurrected by half a source. But the power is not as good as before, and there is no power of the true god. Even if he wants revenge and kills heaven, the demon emperor is willing to gamble on the demon world, and the apocalypse may not be able to kill Wu Huan.