Black Metal Imperial Stout, a.k.a. Suds of Northern Darkness, a.k.a. Iron Sword, a.k.a. El Martillo del Muerte. Black Metal is a cruel and punishing beer fermented by the sheer force of its awesome will. We are pretty sure that Kreator wrote the song “Impossible Brutality” about this beer while drinking it during their Extreme Aggression Tour.