Mistborn is a fantasy book about people with magical abilities called allomancers.
Allomancers "burn" (metabolize metals in the body for magical powers) ingested metals, thereby enhancing various physical and mental capacities.
A brass allomancer is referred to as a soother. An Allomancer burning Brass is able to soothe or guide emotions in a particular direction. An Allomancer can affect a single person or all the individuals in a particular area.