Invective:
An emotionally violent verbal denunciation or attack using strong abusive language


Example:
"He would whip her to make her scream, and whip her to make her hush; and not until overcome be fatigue, would he cease to swing the blood covered cow-skin."
-Frederick Douglass: An American Slave

Explanation:
The purpose of this is to show the cruel conditions that the slaves had to endure. This makes the reader feel bad and feel sympathetic for the slaves, which is what Douglass wants. The strong language like this makes the events more in depth and imaginable to the reader. It also helps set the somber tone and mood.