Place 3-4 mint leaves, 4-5 blueberries, and 1-2 slices of lime in a glass.
Top with the sugar.
Using a muddler or wooden spoon, crush everything together in the bottom of the glass.
Add blueberry syrup and rum.
Add enough ice to fill the glass.
Fill up the glass with club soda.
Give your drink a stir to mix everything together.