Pancha Tapas is an ancient process where one sits inside a ring of fire. The fire gradually turns into ash.
This process is done by yogis to become immune to the 64 different temperatures of the body, masters over their emotions and become immune to several illnesses and, lots more.
Etymology
Pancha Agni Tapas means five fires penance.
Scriptural References
Karthigai Deepam is the day that Devi became enlightened. She did Pancha Agni tapas to merge with Sadashiva. In the evening, Sadashiva appears as pure consciousness in the form of light. He gives half of himself to her and realizing her masculine energy, she becomes Ardhanandeshwara – the perfect blend of masculine and feminine conscious energies. This is the festival of giving enlightenment.
References
http://www.nithyananda.org/content/bhagavad-gita-morning-satsang-25#gsc.tab=0 http://www.nithyananda.org/photo-gallery/nithyananda-diary-1st-july-2015-inner-awakening-day-01-paduka-puja-nithya-kirtan-nithy#gsc.tab=0 http://nithyananda.org/video/samskara-dahana-kriya-easiest-path-enlightenment#gsc.tab=0 http://www.nithyananda.org/video/you-are-rich-because-you-are-hindu-multiple-planes-and-multiple-lives#gsc.tab=0 http://www.nithyananda.org/node?page=15?#gsc.tab=0 http://www.nithyananda.org/events/kumbh-mela-nasik-10-day-program#gsc.tab=0