Walpurgis Night

The witch of stage settings; her nature is helplessness. She symbolizes the fool who continuously spins in circles. The witch's mysteries have been handed down through the course of history; her appellation is "Walpurgis Night." She will continue to rotate aimlessly throughout the world until she completely changes the whole of this age into a drama. When the doll's usual upside-down position reaches the top part of the witch, she completely roils the civilization on the ground in a flash through her gale-like flight. Her true name is unknown.

(Source: Puella Magi Wikia)