Starting today, fans of Rumble Fighter will get valuable in-game rewards for introducing friends to the game, OGPlanet announced. During the Back to School Friends Event, players who invite their friends to join the online-brawling fun of Rumble Fighter will receive a Fire Amulet once at least three of their friends have reached level 7. Their friends will also receive a very special prize - the elusive Stardust Set - for 30 days once they reach level 7.