In a large mixing bowl, combine 4 cups of grape juice with any additional fruit juices you desire, such as pomegranate or cranberry juice for an exciting twist. Stir gently for about 30 seconds until the juices are well blended.

Cover the bowl tightly with plastic wrap or a lid and place it in the refrigerator. Let it chill for at least one hour.

In a large pitcher, pour in 2 liters of lemon-lime soda and gently stir to combine. Add the soda right before serving to maintain its effervescence.

Fill each glass with ice cubes. Carefully pour the punch over the ice, filling each glass about three-quarters full.

For a spooky finish, garnish each glass with a few gummy worms draped over the rim or floating in the punch.

Store any leftovers in an airtight container in the refrigerator and consume within 2 days.