A type of Vidyā (occult science),
that Vidyā, through which one can get the answer to any question by incarnating a deity in a mirror.
'pasiṇāiṃ'ti praśnavidyāḥ yakābhiḥ kṣaumakādiṣu devatāvatāraḥ kriyata iti, tatra kṣaumakaṃ
-vastraṃ, addāgo ādarśaḥ...
(Sthā 10.116 Vṛ Pa 485)