The three potential astras are Vaishnavastra, Pashupatastra and Brahmanda astra. However, these astras cannot harm four principle gods i.e. Brahma, Vishnu, Shiva, and Devi as they are the supreme manifestation of the divine. Any astras cannot harm Hanuman because Brahma gave him a boon that none of the astras would not cause any damage to him.