At Mangala Giri is the famous Laxmi Narasimha temple also visited by Lord Caitanya, is is also known as Sri Panakala Lakshmi Narasimhaswamy .
I have been blessed by Lord Narasimha and have visited this temple 2 times.
You have to go first to the Laxmi YogaNarasimha temple and from there purchase water mixed with Gour ( a kind of datesugar) also known as jaggury water.
The local Sri Vaisnavas will then carry it up the hill and offer it to Lord Narasimha .This water is offered in Lord Narasimhadevas lotusmouth.
The Sri Vaisnavas consider Mangala Giri (auspiscious hill ) to be of of the most important Divya desas (holy places of Lord Visnu) and it is counted among the first 8 according to many Sri Vaisnavas I have talked too.
On this hill Laxmidevi also performed tapasya (austerities ) to please Lord Narasimha, so this place is indeed very auspiscious.
I found this information about Managala Giri that was new to me:
This shape of the hill looks like an elephant. From all the directions, the hill appears in the elephant shape only. There is an interesting legend to show as to how the mountain came into existence. Pariyatra, an ancient king had a son Hrasva Srungi visited all holy and sacred places to regain normal bodily stature and finally visited this holy place of Mangalagiri and stayed for three years performing penance. All the Devathas (Gods) advised him to stay at Mangalagiri and continue to do penance in praise of Lord Vishnu. The father of Hrasva Srungi came with his retinue to take back his son to his kingdom. But Hrasva Srungi took the shape of an elephant to become the abode of Lord Vishnu who is locally known as Panakala Lakshmi Narasimhaswamy.
The Demon Namuchi
Lord Nrsimhadeva has established Himself on the hill in His man-lion form, The Lord Narasimha here is is also called Sudarsana Narasimhaswamy. After great penance, the rakshasa Namuchi obtained a boon from Lord Brahma that he would not be killed by anything wet or dry. He then began to harass Indra and the devathas. Encouraged and supported by Lord Vishnu, Indra commenced destroying the army of rakshasa Namuchi, who died in a cave in Sukshmakaram (small size), giving up his sthulakaram (physical manifestation). Indra dipped Sudarsanam, the disc of Lord Vishnu, into the foam of the ocean and sent it into the cave. Lord Vishnu manifested Himself at the centre of the disc, destroyed the Pranavayuvu (life breath) of the rakshasa with the fire of His exhalation. He thus got the name of Sudarsana Narasimha.
The blood that flowed from the body of the rakshasa seemed to have formed into a pool at the foot of the hill. The devathas themselves were unable to withstand the fire of the anger of Lord Narasimha and they prayed for appeasement. The Lord took amritam (nectar) and cooled down. This was in Krithayugam (Satya Yuga) The Lord said that he would be satisfied with ghee in Threthayuga , with milk in Dwaparayuga and with panakam (jaggery water) in Kaliyuga . Hence, in Kaliyuga the Lord is known as Panakala Lakshmi Narasimhaswamy.
So Lord Narasimha killed the Namuchi demon in form of His Sudarshan Chakra, the Sudardhan Chakra is non different from Lord Narasimha.In the Narayana Kavacha we find these prayers:
: Set into motion by the Supreme Personality of Godhead and wandering in all the four directions, the disc of the Supreme Lord has sharp edges as destructive as the fire of devastation at the end of the millennium. As a blazing fire burns dry grass to ashes with the assistance of the breeze, may that Sudarśana cakra
burn our enemies to ashes.
: May the Supreme Personality of Godhead's holy names, His transcendental forms, His carriers and all the weapons decorating Him as personal associates protect our intelligence, senses, mind and life air from all dangers.
: The subtle and gross cosmic manifestation is material, but nevertheless it is nondifferent from the Supreme Personality of Godhead because He is ultimately the cause of all causes. Cause and effect are factually one because the cause is present in the effect. Therefore the Absolute Truth, the Supreme Personality of Godhead, can destroy all our dangers by any of His potent parts.
Namuci was part of the asuras battle against the Demigods and attacked Indra:
This is expplained in SB 8.11.23
namuciḥ pañca-daśabhiḥ svarṇa-puṅkhair maheṣubhiḥ āhatya vyanadat saṅkhye satoya iva toyadaḥ
Then Namuci, another demon, attacked Indra and injured him with fifteen very powerful golden-feathered arrows, which roared like a cloud full of water
— O King, when Namuci, another demon, saw the killing of both Bala and Pāka, he was full of grief and lamentation. Thus he angrily made a great attempt to kill Indra.
— Being angry and roaring like a lion, the demon Namuci took up a steel spear, which was bound with bells and decorated with ornaments of gold. He loudly cried, “Now you are killed!” Thus coming before Indra to kill him, Namuci released his weapon.
— O King, when Indra, King of heaven, saw this very powerful spear falling toward the ground like a blazing meteor, he immediately cut it to pieces with his arrows. Then, being very angry, he struck Namuci’s shoulder with his thunderbolt to cut off Namuci’s head.
— Although King Indra hurled his thunderbolt at Namuci with great force, it could not even pierce his skin. It is very wonderful that the famed thunderbolt that had pierced the body of Vṛtrāsura could not even slightly injure the skin of Namuci’s neck.
— When Indra saw the thunderbolt return from the enemy, he was very much afraid. He began to wonder whether this had happened because of some miraculous superior power.
— Indra thought: Formerly, when many mountains flying in the sky with wings would fall to the ground and kill people, I cut their wings with this same thunderbolt.
— Vṛtrāsura was the essence of the austerities undergone by Tvaṣṭā, yet the thunderbolt killed him. Indeed, not only he but also many other stalwart heroes, whose very skin could not be injured even by all kinds of weapons, were killed by the same thunderbolt.
— But now, although the same thunderbolt has been released against a less important demon, it has been ineffectual. Therefore, although it was as good as a brahmāstra, it has now become useless like an ordinary rod. I shall therefore hold it no longer.
— Śukadeva Gosvāmī continued: While the morose Indra was lamenting in this way, an ominous, unembodied voice said from the sky, “This demon Namuci is not to be annihilated by anything dry or moist.”
— The voice also said, “O Indra, because I have given this demon the benediction that he will never be killed by any weapon that is dry or moist, you have to think of another way to kill him.”
Iti is not clear if it was Lord Visnu or Lord Brahma speaking this
— After hearing the ominous voice, Indra, with great attention, began to meditate on how to kill the demon. He then saw that foam would be the means, for it is neither moist nor dry.
— Thus Indra, King of heaven, severed Namuci’s head with a weapon of foam, which was neither dry nor moist. Then all the sages satisfied Indra, the exalted personality, by showering flowers and garlands upon him, almost covering him.
— Viśvāvasu and Parāvasu, the two chiefs of the Gandharvas, sang in great happiness. The kettledrums of the demigods sounded, and the Apsarās danced in jubilation
This sloka is important: