At the loudest or scariest moment, cut the picture and sound at once and go to a black screen. Because the ending is never shown, the imagination makes it scarier.
The last cut of a video, right after a scream or a crash, or a cliffhanger that leads into the next episode.
Don't put it in the generation prompt. In the edit, cut the picture and sound together at the frame of the loudest moment. Then add 1 to 3 seconds of black (color=c=black:s=1080x1920:d=2, with silent audio from anullsrc). Don't use a fade.
Two-shot sequence: Shot 1, a man speeds along a night highway in a red car with headlights on and the engine roaring, ending on the car heading toward a wall of fog, 3 seconds; smash cut with no fade to Shot 2, a pure solid black frame with total silence, 2 seconds. All audio stops dead on the cut.
The Blair Witch Project (1999) — After Heather drops the camera and goes quiet, the picture cuts to black (Wikipedia plot summary)
Mr. Zeecon — How the Film Editing of Memento Uses Cut to Black