The pUrva srotas of the tantras of rudra is comprised of the garuDa
tantras, which encompass the glorious prANeshvarI and mR^ityu~njaya
vidyAs. However, less known are the aspects of the regular worship of
mahAdeva in this srotas. The most critical aspect of this the invocation
of the five-fold shiva through the pa~chavaktra chakra. AdhAra of the
worship is viShNu, who shall be first invoked with the formula :
oM bhUr viShNave AdibhUtAya sarvAdhArAya mUrtaye svAhA ||
He is offered an oblation in the fire or a pouring of water.
The the five vedic vaktra mantras of the taittirIya brAhmaNa (or in the case of members of the 4th varNa their equivalents as seen in the sanatkumAra tantraM) along with their tantric emanations are worshipped while meditating upon the maNDala in the appropriate spots. The 3X13 mighty dUtI-s or kalA-s emanating from the faces of shiva are worshipped in order clustered as per their AmnAya (to be detailed later).
Then the mystic gAyatrI of maheshvara is meditated upon by the sadhAka to complete his upAsana .
