I think SIVA was supposed to be on Nessus, in the Exodus black and it was in the vanilla D2 story It was the reason house dusk was tearing apart the ship to begin with , and the Exodus Crash strike was about stopping them from getting it But it got cut, when the story got chopped up again , sadly There are so many things they could have done with SIVA, imagine the vex incorporating it, or it being empowered by light or darkness , lack of imagination on Bungies part