Tyreal should be the bad guy because he could have single-handedly killed the prime evils. Here's how it goes:
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After Baal and his brothers are dead, Tyreal goes against the world and turns heaven into a Hell Sanctuary where he ressurects Diablo and Mephisto. Unfortunately, Baal is beyond death, so Tyreal can not ressurect him. You start off at the monastery, where Mephisto is bringing Tal Rasha back. Then you are trapped in a cage where you are stripped of your weapons and armor etc... You eventually ally a prisoner which helps you escape and then you and the prisoner kill Tal Rasha. After that, you start walking down the road to the forbidden forest, where the prisoner is corrupted by a wandering sorcerer, who is a follower of Tyreal. Then he throws you into the Ruins of the Rogue Encapment. But the wilderness is full of trees and bushes, Making it hard to navigate. Then you kill the prisoner and he then turns into a soul stone, which is used to open the Hell Sanctuary. Then you travel to Hell where you face Mephisto as a boss. When you kill him, Diablo Reincarnated steals the soul stone and sends you back to Earth. You must go back to Hell, which has changed and harder monsters are there. You kill Diablo and grab the soul stone. You go back up to Earth and you have to search for the Haunted Stairs which lead to the Hell Sanctuary. Remember that wandering sorcerer? You must kill her so you can go up the Stairs. Then you must find yourself out of The Maze Of Death and at the end of the Maze is Diablo, Mephisto, Tal Rasha, the wandering sorcerer, and Tyreal, You must kill them one at a time and then after that the world is safe and you become Ruler of the Universe, aka God.
Man, that took me 5 minutes to type it up. LOL
