Fan Yin refers to a situation in Bazi where the Heavenly Stem and Earthly Branch of two pillars completely clash with each other—for example, Year Pillar Jia Zi and Day Pillar Geng Wu. Fan Yin is similar to Tian Ke Di Chong (Heavenly Stem Clash + Earthly Branch Clash), but Fan Yin emphasizes a fully opposing configuration between two pillars, indicating instability, frustration of intentions, intense fluctuations, and emotional unrest.
Examine the four pillars of the Bazi chart to identify any two pillars whose Heavenly Stems clash *and* whose Earthly Branches also clash. For instance, Year Pillar Jia Zi and Day Pillar Geng Wu—Jia clashes with Geng, and Zi clashes with Wu—constitutes Fan Yin. Fan Yin also occurs when a Luck Pillar (Da Yun) or Annual Pillar (Liu Nian) forms a complete Heavenly Stem & Earthly Branch clash with any pillar in the natal chart.
In a Bazi chart with Year Pillar Jia Zi and Day Pillar Geng Wu—Jia clashes with Geng, and Zi clashes with Wu—Year-Day Fan Yin occurs, indicating a destiny sharply divided between youth and middle age.