after the time period of diablo 2, brave adventurers had been chosen to help in the war against hell, the three prime evils had been summoned again by their minions and hell was at its strongest, you have been brought to heaven in the middle of the war, attempting to kill diablo, at the the last quest of act 1, you have to seek and kill diablo, when you hurt him a bit, he gives you a choice, to side with him, or to go against him, if you choose to side with him, you are taken to hell straight away, if you dont, you have to battle with him until he cowardly teleports back to hell. and there are different acts for different sides, some in enemy territory, some in your territory, you have to kill diablo.
after the time period of diablo 2, brave adventurers had been chosen to help in the war against hell, the three prime evils had been summoned again by their minions and hell was at its strongest, you have been brought to heaven in the middle of the war, attempting to kill diablo, at the the last quest of act 1, you have to seek and kill diablo, when you hurt him a bit, he gives you a choice, to side with him, or to go against him, if you choose to side with him, you are taken to hell straight away, if you dont, you have to battle with him until he cowardly teleports back to hell. and there are different acts for different sides, some in enemy territory, some in your territory, you have to kill diablo.
well thats it.