Combine Jamaican dark rum, gold Puerto Rican rum, Demerara rum, fresh lime juice, falernum, Donn's Mix, grenadine, Angostura bitters, and Pernod in an electric blender.
Add 170 grams of cracked ice.
Pulse blend for 3–5 seconds until just combined - do not over-blend.
Pour into a tall tumbler glass.
Garnish with fresh mint leaves.
Donn Beach (Don the Beachcomber) originally kept this recipe secret, using coded ingredient names to prevent staff from replicating it - 'Donn's Mix' is a blend of two parts white grapefruit juice to one part cinnamon syrup, and is key to the cocktail's authentic character.
My Bar Shelf reads your shelf and shows you every cocktail you can make from what you already own, including Zombie.