When one uses the body to find God, it is called Tantra sadhana (Vama Marga).
When one uses the mind to find God, it is called Mantra sadhana.
When one uses energized objects to find God, it is called Yantra sadhana.
This is the gist of Tantra, Mantra and Yantra.
Tantra without a Guru, creates sense addiction.
Mantra without a Guru, creates intellectual madness.
Yantra without a Guru, creates a Frankenstein. These are the dangers of Tantra, Mantra and Yantra sadhna done without a Guru and without a pure heart.