In a cocktail shaker, pour 2 tbsp. light rum, 2 tbsp. gold rum, 1 tbsp. orange curaçao, 1 tbsp. orgeat (almond-flavored syrup), 1 tbsp. rock candy syrup, and 1 tbsp. lime juice. Fill with ice cubes and shake vigorously. Strain into an ice-filled 8- to 12-oz. glass. Slowly pour 2 tbsp. dark rum onto top of drink.