Speak with Eva Levante in the Tower Courtyard.
Represent your class in the Guardian Games by earning Medallions, Laurels, and by completing Contender or Platinum Cards. The more Medallions you deposit in the Tower, the more you'll help your class, and the greater rewards you'll earn.
"You're gonna make a lot of people rich, and a lot of people angry during the Guardian Games. I make the vig either way, so I'll just say, 'Good luck.'" —Prak'kesh the Bookie