In Hinduism, an astra was a supernatural weapon, presided over by a specific deity. The bearer of the weapon is called astradhari.
Specific conditions existed involving the usage of astras, the violation of which could be fatal. Because of the power involved, the knowledge involving an astra was passed in the Guru-shishya tradition from a Guru (teacher) to a Shishya (pupil) by word of mouth alone, and only following the establishment of the student’s character.
Certain astras had to be handed down from the deity involved directly, knowledge of the incantation being insufficient.
Astras come into importance mainly in the Ramayana and Mahabharata, where they are used in the great battles described in each epic. They are depicted as used by archers such as Rama, Lakshman, Arjuna, Meghnad, Karna etc.
The astras were generally invoked into arrows, although they could potentially be used with anything—Ashwatthaman invoked an astra using a blade of grass as his weapon.
Indrajit the son of Ravana, is believed to be the only human who ever possessed the three ultimate weapons of trinity. At a very young age, Indrajit (Meghnada) became the possessor of several supreme celestial weapons, including Brahmastra, Pashupatastra and Vaishnavastra, under the guidance of Shukra, the Guru of the Daityas (demons).Indraastra Indra, god of weather Would bring about a ‘shower’ of arrows from the sky.Brahmaastra Brahma, the Creator Would destroy entire hosts at once. Could also counter most other astras. Mythical equivalent( that some believe to be real and even in this modern age, Attainable). of modern biological missiles to the modern nuclear weapon.In the epic Mahabharata, it is said that the weapon manifest with the single head of Lord Brahma as its tip.In Mahabharata era Parasurama, Bhishma, Drona, Karna, Kripa, Ashwatthama,Arjuna,Yudhishtir and several Maharathis possessed the knowledge to invoke this weapon