Destroying the crystal had made the part of the valley they were in more peaceful, the monsters there withdrew, and the ones that remained were weakened, but it was clear to them that this was not all that was present in the valley.
There were definitely more crystals to be found and destroyed, and they would find and destroy them, for one good reason.
Soul Power.
They had gained a ton of Soul Power after destroying this one crystal, and it was clear to them that doing so was one of the fastest ways to gain soul power and quickly level up, which was the entire reason Lyle and the others had come to the valley.
