Two distinct Jewish ritual traditions - nocturnal study sessions and moonlit shadow divination - converged into a unified observance of Tikkun Leil Hoshana Rabbah through centuries of mystical reinterpretation. Medieval sources first document the practice of Torah reading to complete the annual cycle on this night preceding Hoshana Rabbah, which later expanded into comprehensive prayer and study sessions mirroring Shavuot practices. Parallel to this development, shadow-casting rituals rooted in Talmudic precedent emerged as a means of divining one's fate for the coming year, elaborated through Hasidei Ashkenaz and kabbalistic writings. Analysis of primary sources from medieval responsa through sixteenth-century Safed mystical texts reveals how these originally independent customs became interwoven through kabbalistic influence. The Zoharic concept of Hoshana Rabbah as a final chance for repentance before divine decrees are sealed proved particularly influential in synthesizing these traditions into an integrated ritual complex that endured through the early modern period.