Phase 1: Destroy all the skeletons by either Jinxing them or tossing them around.
Phase 2: While you and Voldemort are engaged in a "tug of war" with your magic, move the beam around so that the thick glowing part blows up the skeletons.
Phase 3: Wait for the statue of Death to land, and then hit it with the thick part of the beam just like you did the skeletons. It'll take a while...first the wings should fall off, and then the rest.