Heroes are the most important force in Guild. Gears, skills, teams and buildings all focus on the development of Heroes. They’re the engine of the Guild.
When enough souls of a hero is collected, that hero can be summoned to join the Guild and fight for you. When you obtain more souls, you can evolve the hero to a higher grade with those souls.
Besides, some lands in Explore can produce Souls and there are Heroes who can be summoned only with Gold appearing in Guild hall from time to time. You can’t miss that!