The golden ball in play.
When the golden ball in the Labyrinth advances all the way to the center, a golden ball is available for play on the board. You must enter the catapult behind the Shaman to convert your silver ball to gold. The gold ball is physically larger than the silver one which changes game play somewhat. Also the golden ball earns 50% more points than the silver one.
Once the golden ball reaches the middle of the labyrinth, the catapult shows as "opened." Entering the catapult will convert your silver ball to a golden one.