Heresy act 2 spoilers below
that Cutscene is Perfection, from fundament to the all of the throne worlds to the first actually first in game look of the Black Terrace and Xivu arath appearance how she's in these bellowing cape that looks to be also her wings.
Also how the echo of navigation Perfectly sides into oryx's chest
And the bones that decorate her main tower in the black terrace, I think that they might be the Jaws of the leviathan, the one from the books of sorrow and one that got the leviathan Eater it's title, it's body was fed to Eir and Yul, but the bones hasn't been mentioned besides the Rib that Rhulk toke.
And one last fun fact. heresiarch means the founder of a heresy or the leader of a heretical sect. Quite appropriate for Eris.
