What is now the Tantric College assembly hall (sngags pa grwa tshang ’du khang) may have been the general assembly hall for the whole monastery before the building of the Great Assembly Hall in the early eighteenth century. It is said to be the oldest of the four large assembly halls. Tradition has it that when he became ruler of Tibet, Lhazang Khan (lha bzang khan, d. 1717) instituted a personal ritual college (sku rim grwa tshang) where ceremonies were carried out exclusively on his behalf. The ritual college had no fixed home, and instead traveled from place to place, meeting in the environs of Lhasa (e.g., at Pabongkha [pha bong kha]) in the winter, and in Jang (byang, northern Tibet) in the summer. When Lhazang Khan resolved to build the Sera (se ra) Great Assembly Hall (sometime after 1705), he decided to use the previous assembly hall as the permanent base for his ritual college. Eventually, the ritual college became the Tantric College (sngags pa rgwa tshang) of Sera.
It would seem that all of the monks of this college came only from Central Tibet. To gain official admission, monks would have to memorize all of the various ritual cycles, and take a series of formal oral examinations. The Tantric College is exclusively dedicated to tantric ritual practice (i.e., there is no philosophical curriculum). Throughout the year, the monks engage in five major ritual cycles (chos thog) related to four deities: Guhyasamāja (twelfth Tibetan month), Yamāntaka (sixth Tibetan month), Cakrasamvara (tenth Tibetan month), Sarvavid (Vairocana, fourth Tibetan month), and the nine long-life gods (tshe dpag lha dgu, second Tibetan month).