The Three Roots (Tibetan: tsa sum) of the Tibetan Buddhist tradition are the lama (Sanskrit: guru), yidam (Sanskrit: ishtadevata), and protector, which may be a khandroma (Sanskrit: dakini) or chökyong (Sanskrit: dharmapala). The Three Roots are the second of three Tibetan Buddhist refuge formulations, the Outer, Inner and Secret forms of the Three Jewels. The 'Outer' form is the 'Triple Gem', (Sanskrit:triratna), the 'Inner' is the Three Roots and the 'Secret' form is the 'Three Bodies' or trikaya of a Buddha. These alternative refuge formulations are employed by those undertaking Deity Yoga and other tantric practices within the Tibetan Buddhist Vajrayana tradition as a means of recognizing the universality of Buddha Nature. The Three Roots are commonly mentioned in the Nyingma and Kagyu