There are many mantra for warding off evils like death and other suffering given in the sacred literature of the Hindu's. These mantra are of various types but the Mrityunjaya mantra has been extolled in sacred literature as being the best. This mantra is addressed to Lord Shiva and is taught in the Rig Veda (7 mandala 59 Chapter) as well as the Yajur Veda (3-60) showing that it is a Sruti having been received by Maharishi Vasistha, the Kula Guru of Bhagavan Sri Ramachandra.
Tryambaka is the name of Lord Shiva as the father of the three worlds - bhu, bhuva and svarga lokas. He is the father and lord of the three mandala's - Surya, Soma and Agni mandala. He is Maheswara, the lord of the three Guna's - Satva, Rajas and Tamas. He is the Sadashiva, the teacher of the three tatvas - Atma tatva, Vidya tatva and Shiva tatva. He is the father (cause and source) of the three energies (agni) - Aavahaniya, Garhapatya and Dakshinagni.