The divinity Marici was a T'ang-import that came to China with Tantric Buddhism. Marici turned Taoist and became a Thunder divinity known as Mother of the Dipper. The presentation illustrates and scrutinizes the development under the perspective of Tao and Fa, the latter term meaning ritual and exorcist methods in religious Taoism. The article compares the findings again referring to Tao and Fa, with the results from a study of an unorthodox coastal cult in Northern Taiwan that is realized in a Yin-miao, which means a cult beyond the limits of officially recognized religion.