The story of Diablo 1, Diablo 2, and Diablo 3 doesn't fully explain all the lore of Diablo. In episode 6 of this Diablo lore series, we discuss the five archangels of the Angiris Council: Tyrael, Malthael, Imperius, Auriel, and Ithereal.

Could any of this lore be relevant to Diablo 4? Could Diablo 4 be a prequel?

Sources:
Book of Cain
http://diablo.wikia.com
https://diablo.gamepedia.com/

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