Some kind of betting minigame where once an hour 2 completely random AI teams are made. Players can then bet X amount of gold prior to the match starting on which of the two teams will win. All the losers betted gold then gets evenly distributed to all winners.
Some kind of cap would have to be put on it like 100,000 or lower so higher gold players just don’t dump all their gold to give to other people. That or a static entry bet, like 10,000.