This is based on opinion. Please don't list it on a work's trope example list.
Nightmare Fuel / A Nightmare on Elm Street 4: The Dream Master
Debbie's death involves her turning into a cockroach in what is clearly a very painful transformation before being crushed in a roach motel. Also, take note that out of the entire movie, Debbie's death was the longest and the most elaborate that Freddy inflicted.