All players either gain or lose medals by winning or losing in the multiplayer mode. This happens even when you’re offline when attacked by other players. If your defense is successful, you gain medals. When defense is unsuccessful (due to enemy receiving at least one war star), you lose your medals. Upon accumulating 100 medals, division promotion match or tier promotion match will be activated. When you lose all your medals, demotion match will be activated.
During off-season, medals will not be gained nor lost