The Third Chime

While the first two bell tolls are scripted, there is a finite amount of time to defeat the enemies in the last room before facing Vaati. If Link runs out of time, Vaati actually successfully completes his ceremony to steak all the light force in Zelda, who was turned into a statue in the beginning, leaving her to be a permanent bird toilet for the rest of her life, essentially killing her.

Example of:
It's a Wonderful Failure