Maha Mantra– mantra for kali yuga.

The prajā-pati is Lord Viṣṇu, and He is the Lord of all living creatures, all worlds, and all beauties, and the protector of everyone. The Lord created this material world to enable the conditioned souls to learn how to perform yajñas (sacrifices) for the satisfaction of Viṣṇu, so that while in the material world they can live very comfortably without anxiety, and after finishing the present material body they can enter into the kingdom of God. That is the whole program for the conditioned soul. By performance of yajña, the conditioned souls gradually become Kṛṣṇa conscious and become godly in all respects. In the Age of Kali, the saṅkīrtana-yajña (the chanting of the names of God) is recommended by the Vedic scriptures, and this transcendental system was introduced by Lord Caitanya for the deliverance of all men in this age. Saṅkīrtana-yajña and Kṛṣṇa consciousness go well together. Lord Kṛṣṇa in His devotional form (as Lord Caitanya) is mentioned in the Śrīmad-Bhāgavatam (11.5.32) as follows, with special reference to the saṅkīrtana-yajña:

kṛṣṇa-varṇaṁ tviṣākṛṣṇaṁ
sāṅgopāṅgāstra-pārṣadam
yajñaiḥ saṅkīrtana-prāyair
yajanti hi su-medhasaḥ

“In this Age of Kali, people who are endowed with sufficient intelligence will worship the Lord, who is accompanied by His associates, by performance of saṅkīrtana-yajña.” Other yajñas prescribed in the Vedic literatures are not easy to perform in this Age of Kali, but the saṅkīrtana-yajña is easy and sublime for all purposes, as recommended in Bhagavad-gītā also (9.14).

https://vedabase.io/en/library/bg/3/10/