The single-player mode in Super Smash Bros. Ultimate that involves spirits is World of Light.
World of Light is Ultimate’s story-driven Adventure Mode. The story begins when Galeem attacks the Smash Bros. universe, defeats nearly every fighter, and turns many characters into Spirits. Kirby escapes and must travel across a large map, rescue fighters, and defeat Spirit-controlled opponents.
Spirits are collectible entities based on characters, creatures, and objects from Nintendo and other game franchises. Players equip them to improve fighters’ abilities or counter special hazards in Spirit Battles. This makes World of Light more than a traditional sequence of fights: exploration, team-building, and puzzle-like battle conditions are central to progression.
A common mix-up is Subspace Emissary, the story mode from Super Smash Bros. Brawl. Ultimate does not bring that mode back. Instead, it incorporates its adventure campaign into the newer Spirits system, with Galeem, Dharkon, and the World of Light map providing the main narrative framework.