Then, why did it take 20 years to make all-out attack and send forth all the legions from Mt. Arreat again? Firstly thought that Azmodan and Belial factions kept fighting each other, but that wouldn't work out in post D2 timeline because both of them seemed to be working together. If not, then why did Ghom accuse the hero from killing lord Belial if he had been his master and ally all along.
I love Diablo games. I'm just asking for my own knowledge.