Tom's rum runner

1.5 oz. Light Rum
3/4 oz. Blackberry Brandy
3/4 oz. Banana Liqueur
1/4 oz. Grenadine
1.5 oz. Orange Juice
1.5 oz. Pineapple Juice
Float 1 oz. Dark Rum

Pour all liquids except dark rum into glass. Fill with ice and stir.
Float dark rum on top and stir gently.