here's a description from the website of the founder of shadow yoga. check out the site for more details and photos.
taken from www.shadowyoga.com
The name Shadow Yoga is derived from the 6th chapter of the ancient tantrik treatise – ‘The Shiva-Svarodaya’ (the birth of the breath of life revealed by the god Shiva). This chapter, entitled ‘Yoga of the Shadow Man’, deals with the intricate manifestations of the shadow and their significance both inside and outside the human organism. The Ashtanga Hrdaya of Vagbhata , a primary ayurvedic text, also contains a chapter on the shadow which deals with diagnostic principles. There is also a story about Allama Prabhudeva, the initiating guru of Gorakshanath (one of the famous forefathers of Hatha Yoga), in which he describes the human body as nothing but layers of frozen shadows. According to Hatha Yogic anatomy the body is composed of three discrete bodies and five sheaths, (coverings or shadows). The practice of Hatha Yoga has evolved with the purpose of dissolving these shadows.
The teaching of the Shadow School is based upon the ancient Hatha Yogic texts, which state that all fixed forms should be designed to develop the practice of freestyle. Freestyle is a necessary step in the cultivation of longevity and enlightenment.
The four fixed forms of Shadow Yoga utilize the guiding principles of Marmasthana, (the Indian system of the 108 vital junctions of the body), to achieve the appropriate combination of positions and rhythmical movements to obtain an unobstructed movement of breath.
PRELIMINARY – BALAKRAMA
OPENING THE SHADOW – CHAYA VIVARANAM
MOVING(CHURNING)THE SHADOW – CHAYA YODDHA SANCHALANAM
CIRCLING THE SHADOW – KARTIKKEYA MANDALA
The four forms are the combination of various warrior (viraparampara) and sun forms (suryanamaskaras) which act as preludes for the asana-vinyasas (primary, intermediate and advanced). The prelude and asana-vinyasa are followed by the inverted asanas of the conclusion which lead into the practice of pranayama and other inner advanced processes like dhyana. The structure of this practice reflects the quintessential form of the gayatri mantra, which consists of prelude, mantra and conclusion (vyahrti, gayatri and siras).