Most of tantra literature scripture are still unpublished. These are not preferred for slight error can result in great harm. These are difficult to perform and require strict discipline and expert supervision.
Tantra is defined as a integrated knowledge that describes a complete system of worship to a cosmic entity that is capable to save a man from all impending dangers.
It should consist of all related ritual to achieve blessings and protection of Higher powers.
This knowlege is gven by Lord Shiva and is called as Agma also. Normally a set of minimum five parts of worship are described in it. they are: Patal, paddhatikavachsahastranam and strotra .
Highest among tantra is Tantric practices of Sri Vidya, being a complete system of worship.
Tantra has all the three parts called Mantra, Yantra and Tantra.
Tantra as a discipline is extremely useful, if one gets associated with a tradition and is initiated by a “parampra Guru”.