Pomegranate-Champagne Punch

2 bottles chilled brut Champagne
1 1/2 cups white rum
1 1/4 cups pomegranate juice
1 large lemon, thinly sliced
Pomegranate seeds
Fresh mint leaves
1 ice block

Bring 1/2 cup water and sugar to a boil in a small saucepan, stirring until sugar dissolves. Simmer 5 minutes. Cool syrup completely.

Combine Champagne, rum, and pomegranate juice in punch bowl. Mix lemon slices, pomegranate seeds, and mint leaves. Add ice block to bowl.