The asuras are generally extremely powerful because of their mystic yogic power. However, as Lord Kṛṣṇa says in Bhagavad-gītā (6.47) :

yoginām api sarveṣāṁ mad-gatenāntarātmanā śraddhāvān bhajate yo māṁ sa me yuktatamo mataḥ

“Of all yogīs, he who always abides in Me with great faith, worshiping Me in transcendental loving service, is most intimately united with Me in yoga and is the highest of all.” The actual purpose of mystic yoga is to concentrate one’s attention fully on the Personality of Godhead, Kṛṣṇa, and always think of Him ( mad-gatenāntarātmanā ). To attain such perfection, one must undergo a certain process — haṭha-yoga — and through this yoga system the practitioner achieves some uncommon mystic power. The asuras, however, instead of becoming devotees of Kṛṣṇa, utilize this mystic power for their personal sense gratification. Maya Dānava, for example, is mentioned here as mahā-yogī, a great mystic, but his business was to help the asuras. Nowadays we are actually seeing that there are some yogīs who cater to the senses of materialists, and there are imposters who advertise themselves as God. Maya Dānava was such a person, a god among the demons, and he could perform some wonderful feats, one of which is described here: he made a well filled with nectar and dipped the asuras into that nectarean well. This nectar was known as mṛta-sanjīvayitari, for it could bring a dead body to life. Mṛta-sanjīvayitari is also an Āyurvedic preparation. It is a kind of liquor that invigorates even a person on the verge of death.