How Genjutsu prompts work
Genjutsu is a reference-driven video model, not a text-to-video model. Your source clip already carries the motion, the camera and the timing, so the prompt never has to describe them. It only has to say which element changes and what that element becomes.
That is why good Genjutsu prompts are short. A long cinematic paragraph leaves the model nowhere to apply your reference images, while a two line instruction about a single element usually lands on the first attempt.