With all of the new hints at savathun, and the fact that the leviathan is one of the beings in the books of sorrow, it is likely that oryx's cunning sister will appear in the raid. It is also possible that the cabal emperor will play a role, since in the limited edition it states he is imprisoned in the leviathan. The question is whether or not these are the same leviathan or a coincedence. let me know what you think.