He had beheld the latent power of the Nephalem hero. He had seen the actions of Zoltun Kulle, a Human who had embraced evil.
In truth, Malthael had seen these events. Regardless, after Diablo's defeat in his siege of the High Heavens, a now mortal Tyrael took Malthael's place as the Aspect of Wisdom. Some speculated that he haunted the Halls of Pandemonium, seeking answers to the unknowable mysteries of life and death. His departure broke the unity of the Angiris Council. Just prior to this, he had apparently taken a greater interest in Humanity. Malthael disappeared after the destruction of the Worldstone.
