Scout Heroes were powerful Scouts which assisted in the war between the settlers of Shakuras and Ulrezaj.
Ulrezaj had stolen a sacred khaydarin crystal from Shakuras, and while tracking it, the protoss discovered that Ulrezaj had created five warped khaydarin crystals on Char. He was using them to control zerg minions.
Zeratul needed a dark archon to destroy the warped crystals, as only its psychic fury was capable of it. The Dark Archon Hero was accompanied by a pair of Scout Heroes as well as several other heroes.