Symphony of Death
Record your enemies' screams. Defeat base combatants to record discomfort. Defeat elites and minibosses to record pain. Defeat bosses and other Guardians to record anguish. Screams gathered on the Moon count more.
"And with their screams, we shall map the language of pain and scrawl a new masterpiece—the vile sheet music of damnation, a strange, new song of bloodied ear, carved flesh, and shattered bone, so that their symphony of torment may be turned against them." —Toland, the Shattered