In a shaker filled with ice, combine the spiced citrus juice, rum, vodka, and cherry liqueur. Shake until well combined and pour into a glass. Top with champagne and 1 drop of Peychaud's bitters.
Combine the grapefruit, orange, lemon, and lime juices in a large mixing bowl. Add the mint and cardamon. Cover, refrigerate and allow the mixture to sit for 2-3 days, stirring every day. Strain and refrigerate for up to 1 week.