Fill beverage vessel ⅓ full with ice then pour in Hennessy, lemon juice, hibiscus syrup, gin, ginger liqueur, Grand Marnier, and sugar. Stir until sugar is dissolved and liquid is a uniform color.
12 ounces Hennessy cognac, 8 ounces lemon juice, 8 ounces hibiscus syrup, 2 ounces gin, 2 ounces ginger liqueur, 2 ounces Grand Marnier, ice, ¾ cup cane sugar