The sadAshiva chakra is composed of five chakras: tatpuruSha, aghora, vAmadeva, sadyojAta and IshAna.
Here the word chakra refers to yantra (maNDala), mUrti and mantra and hence a sort of sa~Nketa traya for the five-fold diversity is seen in all these aspects. The origin of the mantra chakra is from the mantra shuddha praNava with its five components: a, u, ma, bindu and nAda. These represent tatpuruShAdi mUrtis. From the praNava arises the five lettered mahAmantra popularly known as shuddha pa~nchAkSharI mantra. The five letters of this mantra represent the five mUrtis (tatpuruShAdayaH). From each of the letters of this mantra originate five panchAkSharI mantras known as the much(y)a panchAkSharas:
IshAna, sadyojAta, vamadeva, aghora and tatpuruSha panchAkSharas.
From each letter of these mantras, five panchAkSharas originate i.e. from every mukhya pa~nchAkShara mantra, twenty-five panchAkShara mantras emanate:
tatpuruSha panchAkShara, aghora pa~nchAkShara, vAmadeva pa~nchAkShara, sadyojAta pa~nchAkShara, IshAna pa~nchAkShara
ananta, aghora, saumya, rudra, hamsa, Atma, Aj~nA, madana, mAyA, mantra, amR^ita, prapa~ncha, sArasvata, skanda, mUla, mahA, kailAsa, mR^ityu~njaya, lakShmI, kShipra, Ananda, ana~Nga, shAmbhava, jvAlA and sarvasiddhi panchAkSharas
vidveSha, savya, satya, brahma, vishva, varuNa, samudrashoShaNa, garuDa, gaja, bhramara, saMgrAma, yoginI, gaNa, shArabha, gandharva, vidyAdhara, sandhAna, sR^iShTi, samhAra, chitra, vyaShTi, samaShTi, vaishvAnara, parjanya and yakSha pa~nchAkSharas
stambhana, praj~nA, stotra, vimAna, mAnasa, dhenu, purUhUta, icChA, laghu, saura, baindava, sa~nchAra, Aloka, vij~nAna, khechara, pa~nchasadAkhya, manovega, shubha, gIrvANa, svarga, viSha, sundara, ghaNTA, sa~njIvana and AkhaNDala panchAksharas
bhedana, prAjApatya, mahAbala, nirvana, nayana, giri, viShNu, ucchaishrava, mandAkinI, samvarta, aghamarShaNa, anAhata, megha, pavana, siddhi, yaj~na, pUjA, parimala, sasya, dik, jihvA, karNa, chit, j~nAna and sambhoga panchAkSharas
prAsAda, prAsAdagochara, prAsAdasundara, prAsAdashekhara, prAsAdasaura, prAsAdabandhana, prAsAdabhujanga, prAsAdakamala, prAsAdachandra, prAsAdavidyAdhara, prAsAdavij~nAna, prAsAdachintAmaNi, prAsAdadIpaka, prAsAdavidyatanu, prAsAdakamalAnanda, prAsAdakavacha, prAsAdaratnAkara, prAsAdakaustubha, prAsAdalakShaNa, prAsAdakuNDalI, prAsAdachUDAmaNi, prAsAdapArameshvarIya, prAsAdashaiva, prAsAdashakti and mahAprAsAda panchakshara mantras
Each of the 125 panchAkShara mantras are said to confer different siddhis. For example, the siddhi associated with prAsAdakamalAnanda is bhuvanAdhva darshana, prAsAda chintAmaNi is somamaNDala darshana, karNa panchAkShara is karNa siddhi, nayana panchAkshara is dUradarshana siddhi, khechara panchAkShara is AkAshagamana siddhi and so on.
Thus, this results in a total of 125 + 5 + 1 = 131 mantras (excluding praNava) which again amounts to the number 5 (1+3+1). As these 131 mantras with praNava acting as mantra vIrya for each of them are hidden within the prAsAda, this great mantra of sadAshiva is termed as the seed or bIja of every mantra belonging to shaivAmnAya. Hence, the UrdhvAmnAya tantra describes the siddhi of prAsAda as equivalent to the siddhi of the entire gamut of shaiva mantras. When we speak of prAsAda, the reference here is to shuddha prAsAda (of shaivAmnAya) but due to its presence within parA prAsAda and prAsAda parA, this would hold good even in the case of these mantras belonging to shAmbhavAmnAya. Hence it is said regarding mahAprAsAda mantra:
tamAchAryaM vijAnIhi dvAdashArNapradaM shive |
guruH prAsAdadAtA syAdupAdhyAyaH prakIrtitaH ||
ShaDakSharI pradAtA tu sA~NgopA~NgaM mahAmanum |
dadan sa paramAchAryo saiva deshikarADiti ||
imaM manuM naro yastu sakR^ijjapati bhUtale |
guruM santoShya yatnena pUjayitvA svakardhanaiH ||
sa eva muktisAmrAjyapadavIbhA~N na saMshayaH |
shaivaM ShaDakSharImAhuH pUrvA~NgaM shrutayaH shive ||
dvAdasharNaM tathA prAhuruttarA~NgaM shivAgamAH |
prAsAdamAhurhR^idayaM sarvAmnAyagatAH shive ||
vidyAvihInopi dhanairvihInaH putrairvihInopi yashasA vihInaH |
vidyAmimAM kAmitakalpavallIM sA~NgAM bruvan pAtakasa~NghamuktaH ||
shivopi chAhaM svamukhairyutaH san vidhishcha vA viShNurathAmarA vA |
mAhAtmyamasyAH prabhavanti nAtra kiM vaktumanye prabhavanti mUDhAH ||
The anuShThAna of sadAshiva chakra and panchAkShara prAsAda rashmi nyAsa are performed during pradoSha and importantly on the last prahara of Mahashivratri. The observance of sadAshiva chakra in its aspects of mantra, mUrti and mandala grants panchAnga shuddhi without which inner alchemy has been declared as unattainable by the rasa siddhas.