This project aims to explore how the 11th-century Indian Buddhist scholar-monk Ratnākaraśānti employed arguments from the Buddhist logico-epistemological school to justify maṇḍala rituals and spiritual (yogic) practices within a tantric framework. Two main supersectarian currents of Indian Buddhism—Buddhist tantrism and Buddhist logic and epistemology—began to converge after the 6th century. By the 11th century, the integration of these two currents into Buddhist monasticism had been longstanding, resulting in the justification of spiritual practices involving tantric rituals and visualisations through arguments from the logico-epistemological school. Scholars have only recently begun to examine the interconnectedness of these two currents, which significantly influenced late Indian Buddhism and had further impact on Tibet. Through historical and philological analysis, the project aims to contextualise Ratnākaraśānti’s works within the history of Buddhist philosophy and tantric exegesis, highlighting his indebtedness to figures like the Buddhist epistemologist Dharmakīrti and scholars from the tantric Jñānapāda school of Guhyasamāja exegesis. By providing critical editions and English translations of previously understudied text passages from Ratnākaraśānti’s tantric works, especially those extant only in Tibetan such as the *Kusumāñjali and the *Guhyasamājamaṇḍalavidhiṭīkā, along with selected passages from works of the Jñānapāda school scholar-monks, the project aims to shed light on the relationship between Buddhist epistemology and tantra, as well as between Buddhist theory and practice. It will thus offer both a wider perspective and a deeper understanding of the pre-modern intellectual landscape of South Asia. The output of this project will be of interest to a wide range of scholars specialising in Buddhist Studies, classical Indian philosophy, Indian tantric traditions, Sanskrit Studies, and Tibetan Studies.