Add the pineapple chunks and 1 cup of ice to a blender. Pulse a few times until the fruit is finely chopped.
Pour in the light rum, dark rum, brandy, gin, orgeat syrup, pineapple juice, orange juice, and lemon juice. Blend for about 15–20 seconds until smooth.
Taste the mixture before serving. Add a splash of lemon juice if it's too sweet or a little more orgeat if it's too tart.
Fill a large Scorpion bowl or punch bowl with the large ice cubes. The bigger cubes melt slowly and keep the drink flavorful.
Pour the blended cocktail over the ice. The mixture should look smooth, frothy, and lightly slushy.
Garnish with orange slices, pineapple chunks, and maraschino cherries. Arrange the fruit around the bowl for a colorful presentation.
If using a Scorpion bowl with a center reservoir, carefully add the overproof rum and light it using a long lighter. Always extinguish the flame before serving.
Insert long straws, serve immediately, and enjoy while the drink is cold and fresh.