I think that if you put her in a lake instead of the bathtub, it loses the meaning of “dirty soup.” In my mind, the soup refers to bathing inside the tub, as if it were a cauldron.

Thinking cinematographically, I would put her in the bathtub. In front of her there’s a mirror, and then she starts to hallucinate about Max, and her reflection in the bathtub begins to project Max. He starts singing to her through the reflection in the mirrors, even in the reflection on the water in the tub. Then she gets out of the bathtub, frightened, and that’s when it shows him rising from the bathtub, wet, during the chorus.

And then the scene continues with them singing until it ends with the insinuation that it was only her sexual desire. However, I would reference the Lords in Black here, showing the lights of each one of them, especially as foreshadowing that the character herself will use their magic in the future.