Place the cherry juice, reposado tequila, lime juice, cherry liqueur, Simple Syrup and mezcal in a mixing tin, add large ice and shake vigorously. Strain into a highball glass over fresh ice. Garnish with a spear of fresh cherries.
Combine the sugar and 1 cup water in a small saucepan and bring to a boil. Cook, stirring, until the sugar dissolves. Remove from the heat and let cool completely. Keep covered in the refrigerator up to 1 month.