In the end, Luke waited until the moment those two were exhausted and then froze both of them at the same time. Once he used them with the Essence Sword, they died, and Luke looked for the next targets. Still, Luke had a hard time doing that since all the landmarks of that world had been destroyed. The landmarks now were craters, and they were all too similar to each other to be called that.
After flying around for three days, Luke realized that most of the enemies had already vanished. In the first place, the real powerful ones would crush the others as fast as possible. Considering that the second floor essentially decreased the number of overlords by half, it wasn't surprising that the numbers on the third level would be below.