The "Invisible & Ineluctable Casino" was what flamboyant gambler Drawmas Sma'Da termed his operation that covered wagers on the various battles and conflicts during the Galactic Civil War. Sma'Da would make odds, accept bets on either side of the outcome, then pay off and collect whenever that particular event was over. It was seen as a shadow of the actual war. No matter the outcome— either in terms of wagers or conflicts —Sma'Da seemed to come out ahead.
It was due to Sma'Da's clever wagering and seemingly impossible luck that brought him to the attention of Emperor Palpatine.