This is my theory for the location bonus:
In each of the hero Banners, the hero has a certain location as a background. (The hermit has a forest, the thief has the mines, etc)
I think that when your heroes are in the same area as their background shows the location bonus is activated for that particular hero.
Click + if you want to get something besides GP bonuses on your next purchase and MP points.I just got four MP points in a row from the roulette. b0ss, plz.