Add the mango nectar, passionfruit juice, pineapple juice, lime juice, and honey to a blender. Blend on medium speed for 20 seconds until the honey fully dissolves and the mixture is smooth.
Pour the blended base into a large pitcher and place it in the refrigerator for at least 15 minutes to chill.
Right before serving, slowly stir the chilled sparkling water into the pitcher to add fizz without losing too many bubbles.
Fill four glasses with ice cubes. Pour the brew over the ice until each glass is three-quarters full.
Add a mango slice and a passionfruit half to the rim of each glass as garnish.