Last Breath is a fan-made Undertale project that reimagines the Sans boss fight as a longer, harder encounter, with Phase 3 marking its most intense stage. Its music, including the track labelled An Enigmatic Encounter, circulated through YouTube videos, gameplay edits and soundboards, where short excerpts became shorthand for a climactic showdown. Because Undertale's boss music already carries strong recognition among players, the Phase 3 excerpt still works instantly in gaming montages, reaction edits and dramatic memes without needing any explanation.