Was the creation of the dream bubbles due to feferi being a life player, or her unique lusus? And did she die because of that or was it something else? I have a bad memory I'm sorry :(

She died because Eridan was an asshole and nothing in relation to anyone. She did make the Bubbles BOTH Because she’s the Witch of Life and because of her Lusus. Considering Gl’bgolyb as her Familiar, her Classpect and her Communion with the Horrorterrors are actually intrinsically tied together.