Once “freed,” Ruin was able to affect the world more directly. The most obvious way he did this was by making the Ashmounts emit more ash and the earth begin to break apart. As a matter of fact, I believe that much of Ruin’s energy during those last days was dedicated to these tasks. He was also able to affect and control far more people than before. Where he had once influenced only a few select individuals, he could now direct entire koloss armies.
