The gist of mantra sadhana:

Mantra Rupa bhaved Deva, Deva Rupa gururbhaved l

Gururoopa bhaved aatma, aatmarupi manurbhaved ll

Mantra transforms from shabda bramha to saguna devata, devata transfigures into guru roopa, the external guru roopa metamorphoses to becomes one with the aatma of practitioner and the practitioner inturn gets aatma bodha and becomes one with the supreme consciousness.

Thus, guru, devata and mantra are one. One who realises this gets the ultimate accomplishment.

🙏 Namo Narasimha 🙏