Musically, Götterdämmerung, like its predecessors in this Barcelona production, has strengths and flaws. Fortunately, Kupfer's interpretation places Brünnhilde and Hagen at its center and the singers are well up to the task. Deborah Polaski's final scene, so critical to any performance of the cycle, is excellent, the voice warm, the emotions palpable. Her moving performance here is ample compensation for the touch of vocal hardness she displays in the opening scenes. As Hagen, the veteran bass M...