Trace On comes from Fate/stay night, where it is the trigger phrase for projection magic, the ability to recreate weapons from memory. It is most closely associated with Archer, the Servant version of Shirou Emiya, whose Unlimited Blade Works makes the line a shorthand for his fighting style. The phrase travelled beyond the original visual novel through its anime adaptations, fan edits, and short-form videos, where a single spoken cue can signal an incoming transformation. Its brevity and dramatic delivery have kept it popular for anime edits and reaction clips.