Willian came out of the palace with Oz and said, "If we placed the ice mirrors all over the place, then it may take away the darkness, but Nether can still use his strength to break them."
Oz nodded and said, "Yes, indeed. The darkness in the place is like a tide, if the dam is broken, then the water will come back flooding in. Nether will be invulnerable again."
The hunter nodded and said, "What shall we do?"
Oz said, "We can try and contain Nether in one zone."
Willian understood his intent. What the guardian meant was to cast ice mirrors in a specific zone and let it isolate the darkness outside, then they can lure Nether into that zone. However, the bait might die in the attempt.