Malthael is a character in diablo 3, and the relevant plot is as follows:

In diablo 3, Malthael used to be the wisdom archangel in the highest heaven, and together with the heroic archangel Price, the justice archangel tyrael, the destiny archangel Ethel and the hope archangel arie, he formed an angel committee in a higher heaven. He mainly played a mediating role in parliament, but he didn't ignore it in the war with the devil. Even the proud Prius admitted that he was "second only to me in heaven". However, when Archangel Inarius left, Malthael suddenly became interested in death. He began to study the power of death, delved into the mystery between life and death, and turned these into his own powerful power, making himself the embodiment of death. He began to participate less and less in the work of parliament and rarely appeared in heaven. After the shelter was discovered, Malthael abstained in the voting on human survival. His reason is that everything will be over, leaving me alone. He despises these human beings who can never get rid of the fate of death. Then he abandoned the highest heaven and disappeared.

After disappearing in Malthael for a long time, Diablo, the great fiend who is the source of all evil in the combination of seven demons, was defeated by Nai Feitian Warriors. When tyrael was preparing to hide the soul stone of darkness that sealed him underground, he suddenly appeared with a reaper's sickle, killed all the "Horatim" human guards around tyrael and took away the soul stone of darkness. The once wise archangel decided to destroy all sentient beings, including all mankind, with the blood of the devil.