Inferno Shield.

Archangel Izual was defeated in a raid on Hellfore, and in the words of Archangel Tyrael, "his holy soul was locked in the depths of Hell, his will sealed in the body of a horrible monster". Regardless of the embellishments, the fact remains that the Archangel IZUAL finally defected to Hell and became a Fallen Angel.

After the emergence of humans, the battles between Heaven and Hell were rarely fought outright, and instead, humans were manipulated into simulation exercises, and the war was renamed "The sin war", which is a reference to the biblical word "sin". The sin war", "sin" is a reference to the original sin in the bible, it's a real bummer, the war is not over and you still have to put the sin on the head of human beings.