In a blender, combine 45ml of aged Jamaican rum, 45ml of gold Puerto Rican rum, 30ml of overproof Demerara rum, 22.5ml of lime juice, and 15ml of falernum.
Add 2 teaspoons of grapefruit juice, 1 teaspoon of cinnamon syrup, 1 teaspoon of grenadine, ⅛ teaspoon of pastis, and 1 dash of Angostura bitters.
Add ¾ cup of crushed ice, blend, and pour into a Collins glass. Garnish with a mint sprig.
