ॐ ह्रीं क्ष्रौं
Narasimha is the foremost Agni tatwa. Agni is the reason for sight. The sight does not just mean seeing. It also means vision. This is the reason we worship a form of Agni when we learn Jyotish. Jyotish is the ability to visualize or to see an event manifesting in the future. There are many forms of Agni, but the most sacred in the form of Narasimha.
The mantra om hrīṁ kṣrauṁ has a very specific meaning from the parampara. This is chanted during pranayama in a specific sequence. The first is the OM. This is to activate the heart chakra ( Anahata) where Lord Narasimha will be seated. The next is hrīṁ which activated the throat chakra (viśuddhi). This is the center of speech of Vak. Every Jyotish must have a good Vak Shudhi, meaning whatever is spoken is pure, is of Satwa guna. The next syllable is kṣrauṁ which activates the Sahasrara chakra. This removes the ignorance in a Jyotish and blesses us with wisdom.