I have two things to say to that. 1) the original concept art for the black garden made it look like it was inside of a sphere and 2) Rasputin mentions hurting IT with aurora knives, in the ghost fragment the traveler in the "Dreams of Alpha Lupi" he talks about the knives that injured "you"(bot sure who he is referring too) and that they injured more than "your" body, possibly injured a spirit? A soul? An aura? Which, when looked at in certain light could be much like an aurora