This sound comes from The Avengers score, associated with composer Alan Silvestri and the heroic theme used for Marvel's team-up moments. Short cuts of the theme spread online through fan edits, meme compilations and cinematic reaction videos because the brass phrase communicates instant importance. Creators still use it when they want a quick superhero payoff without much context, especially for entrances, transformations and exaggerated “assemble” style reveals. It also overlaps with the same dramatic edit space as the Prowler Sound Effect, though the tone here is triumphant rather than ominous.