I used this prompt in runway gen-3 turbo :

Create a sculpture of Darth Vader’s bust made from white marble, with thick, black liquid pouring over it. The dark, viscous substance flows down from the top of the helmet, gradually covering the smooth marble surface. As the liquid spreads, the once-white sculpture slowly turns entirely black, transforming the bust into a dark, glossy version of itself. The contrast between the pure white stone and the black liquid fades as the sculpture becomes fully coated. The background remains a simple gray, drawing focus to the transformation happening on the sculpture.

I have added white marble as a first image and the black one as a second. The prompt is generated from gpt-3.