While there is no guaranteed method for finding the loosest machines at Mystic Lake Casino, there are a few tips and strategies you can use to increase your chances of winning big: Mystic Lake Casino offers a variety of slot machines with different payout percentages, and some machines are known to have higher payouts than others. What Are the Best Slots to Play at Mystic Lake Casino? However, it’s important to remember that these percentages are based on long-term play and are not a guarantee of immediate winnings. Slot machines with higher payout percentages are known as “loose” machines, and these machines are more likely to pay out winnings over time.