I said from day 1 that the raid for year 1 should of been the Almighty. It's introduced into the lore and just makes a whole lot more sense than Leviathan as a whole. We could of went there to disable it once and for all. The next raid lair, they found a Vex Mind(Argos) on Mercury (the planet the Almighty was farming and the location of the DLC) that was taking it over that we had to stop before it assimilated it. The final one, Val Kilmer went to try to reactivate the Almighty in one final attempt to kill us all. It's a much stronger story. Leviathan and Calus should of been arriving with the Penumbra DLC. It's already about the Leviathan anyway and would of fell as a much more natural story. As it is now, it feels simply shoehorned in. Regardless though, I think that in LW they did some things just for the sake of difficulty, not because they made sense.