Would destroy target completely, irrespective of target's nature. Infallible. This weapon had to be obtained from Shiva directly.
In Hindu History, is an irresistible and most destructive personal weapon of Shiva, Kali and Adi Parasakthi discharged by the mind, the eyes, words, or a bow. Never to be used against lesser enemies or by lesser warriors, the Pashupatastra is capable of destroying creation and vanquishing all beings. Pashupatastra is the weapon of Pashupatinath, the most important of all Shiva temples, located in Kathmandu, Nepal.
At various times, Lord Shiva also bestowed the use of this astra on other famed personalities. One of these was Meghnad, the son of Ravana, who used it against Laksmana in the Treta Yuga. Indrajit is also said to have used this astra against Rama and Laksmana. In Dvapara Yuga, Arjuna employed Pashupati in the Kurukshetra war to kill Jayadratha, and he also used it against Karna and Ashwathama.
In the Udyoga Parva of Mahabharata, Grandfather Bhisma states:
"Regarding Arjuna, who has Lord Narayana as his charioteer, there is none amongst the warriors on both sides who can be his equal. Indeed, even amongst the gods and demons, there is none his equal. The chariot on which Arjuna will fight is celestial and cannot be destroyed. The monkey that rides on the banner is also divine and cannot be slain. The Gandiva bow and the two inexhaustible quivers of Partha were given to him by Varuna. He has obtained all the celestial weapons from the heavenly gods, including the thunderbolt weapon and the Pashupatiastra. Only myself and Drona can challenge him. However, he is young and skillful, whereas we are old and our energy is easily spent."
Pashupatiastra can be discharged simply by a thought, by using one's eyes, or by mantra. It can also be activated and delivered with a bow. The following mantra is said to be the one used for deploying Pashupatiastra, although it is locked during the Kali-yuga:
This astra is capable of destroying the manifest creation and vanquishing all beings. However, it can only be used for conducting dharmic activities, also described in the Udyoga Parva:
"In the presence of all the great fighters on his side, Yudhisthira inquired from Arjuna, O Dhananjaya, I have heard that Bhishma, our grandsire, has vowed to annihilate our army in one month's time. Drona has vowed the same and Kripa has vowed two months. Drona's son has said ten days and the wicked son of Radha has vowed five days. Therefore, I ask you, O Phalguna, how long will it take you to destroy the enemy?
Do not have any fear, O King, Arjuna replied. Unquestionably I say that with Vasudeva as my chariot driver, I can decimate the three worlds in a mere twinkling of an eye. I have in my possession the Pashupatiastra given to me by Lord Shiva. It is not, however, proper to use it on common warriors. We shall, though, kill the enemy in a fair fight. All the great maharathis will slaughter the enemy forces, and even yourself will be competent to annihilate Duryodhana's forces."
The village of Deo Tibba, located in the Kullu Valley of Himachal Pradesh, is the place where Arjuna went to perform austerities in order to get the use of Pashupatiastra. He came to this place to do penance on the advice of Srila Vyasa. Arjuna's pastimes at Deo Tibba, which is located about 3,000 feet above sea level, are depicted in the rock-cut monument at Mahabalipuram that is commonly referred to as 'Arjuna's Penance'.
The mantra to obtain the weapon is sealed by Lord Shiva so that it cannot be misused under any circumstances, especially in the Kali Yuga. The pashupatastra can be neutralized only through another pashupatastra or any other astra (weapon) whose presiding deity is Lord Vishnu.
Arjuna’s pastimes with the famed Pashupatiastra of Lord Shiva are described at several places in the Mahabharata. In the Drona Parva there is a description of Arjuna’s vow to kill Jayadratha, and Drona’s vow to save him. Lord Krsna suggested that Arjuna fortify himself by seeking a boon from Shiva, thus Arjuna performed tapas to obtain the use of Pashupatiastra.
While Krsna was giving Arjuna this advice to approach Shiva, both he and Arjuna began to contemplate the glories of Shiva, and praise him. But even before this scene, in the Vana Parva, Arjuna had a pastime of fighting with Shiva, which also resulted in his getting the use of Pashupatiastra.
There is another pastime which took place while the Pandavas were living in Arshtisena asrama, at Gandhamadana. Lord Indra asked for guru-dakshina from Arjuna, in exchange for teaching him how to use the great astras. Indra instructed Arjuna to kill the Nivatakavachas, who were the enemies of Indra. Complying with the request, Arjuna employed the Pashupati-astra to kill the enemies as guru-dakshina for his great teacher.
There is yet another pastime often referred to in regard to Pashupatiastra. On this occasion, Arjuna went to Indrakila Hill to engage in penance. He meditated upon Lord Vishnu, manifest in the form of Shiva. At this time, the demon Mukasura came along in the form of a pig, with plans to kill Arjuna.
While Arjuna was throwing arrows at the demon, Shiva arrived with Parvati, and he also began hurling arrows at the pig. Shiva said that that he had come for hunting and the pig belonged to him, and that Arjuna was not a hunter. A fight subsequently broke out between Shiva and Arjuna, during which Arjuna collapsed.
Arjuna then prepared a Shivalinga and worshipped it with flowers. To his surprise, the flowers manifested on the head of Shiva the hunter, and Arjuna realized who this great hunter was. He then prostrated himself at Shiva’s feet and in return, Shiva gave Arjuna the Pashupati-astra.
This Pashupatiastra is also described as having been given by Lord Visnu, originally being the Brahmastra which Vishnu gave to Shiva. This is associated with the Gayatri hymn. Lord Narayana, present in the Surya-mandala, is the presiding Deity for the Gayatri. When Arjuna received the Gayatra, Narayana appeared before him and Lord Shiva also blessed him, requesting that he go to Indraloka to get astras from the other deities.
We begin our final segment on the Pashupatiastra with a description of the personification of this transcendental weapon – Pashupata, who is one of Lord Shiva's topmost ganas. In Chapters 317 to 326 of the Agni Purana, Lord Shiva is describing to Skanda the worship of his ganas, Vagishwari, Aghora, Pashupata, Rudra, and Gauri.
It is not surprising that Lord Shiva should be offering this explanation to Skanda, who is also known as Murugan, Kartikeya or Subramanian. According to Mahabharata, Skanda was born of Agni and Svaha, and became a great general, leading an army of demigods in warfare. The Satapatha Brahmana refers to him as a son of Rudra. In Bhagavad-gita 10.24, Krsna says, "of generals I am Kartikeya", and in his Bhaktivedanta Purport, Srila Prabhupada says:
"And as Indra is the chief of all kings, similarly Skanda, or Kartikeya, the son of Parvati and Lord Siva, is the chief of all military commanders."
In the latter half of Agni Purana, Lord Shiva is explaining to Skanda how he may be worshipped in the form of Pashupati-astra, who is also personified by his gana Pashupata.
The narrator of the Agni Purana is the fire-god himself, Lord Agni. Agni related the subject matter of this Purana to Vashishtha Rishi, who in turn passed the knowledge on to Vyasadeva. Vyasadeva's disciple Suta then heard the Purana, and delivered it to Shaunaka and the assembled sages at Naimisharanya.
There is an interesting description of Shiva's warrior ganas in the Shanti Parva (108:16-32) of Mahabharata. Yudhisthira is asking Bhishma about the ganas and how they operate in proliferating and defending themselves. Given the ganas' close association with various aspects of battle, we can see a correspondence between the gana Pashupata and Lord Shiva's weapon, Pashupatiastra.
Hearing these words (of Krishna), Dhananjaya, licking the corners of his mouth, quickly shot that arrow which he had taken up for Jayadratha's slaughter, that arrow, viz., whose touch resembled that of Indra's thunder, which was inspired with mantras and converted into a celestial weapon, which was capable of bearing any strain, and which had always been worshipped with incense and garlands. That shaft, sped from Gandiva, coursing swiftly, snatched Jayadratha's head away, like a hawk snatching away a smaller bird from the top of a tree. Dhananjaya, then, with his shafts, sent that head along in the welkin (without allowing it to fall down
Finally, we find an excellent passage describing how Arjuna learned to use the Pashupatiastra, from the end of Chapter Four of the Drona Parva of Mahabharata, entitled ‘Arjuna Vows to Kill Jayadratha':
"Meanwhile, as Arjuna lay on his bed, he was contemplating the next days activities. As he thought deeply of Lord Krishna, he fell asleep. He then had a dream, and in that dream, Lord Krishna came to him. "You possess the weapon given by Lord Shiva," He said. "It is called the Pashupatra astra. However, you do not know how to use this weapon. Let us go together to Lord Shiva's abode and receive instructions on how this weapon may be implored to kill Jayadratha." Taking Arjuna by the hand, Lord Krishna took him to Kailasa. Passing through many beautiful regions, those two heroes, Nara and Narayana, finally came to the abode of Lord Shiva. Upon seeing the Supreme Personality of Godhead, Lord Krishna, Lord Shiva offered his obeisances. Lord Krishna is the source of all the devas including Lord Shiva and Lord Brahma. After offering his worship to Lord Krishna, Lord Shiva inquired from them, "You are both welcome here. Please tell me the reason for your journey, for I will satisfy your desires, and grant whatever you wish."
"You have previously given me the celestial weapon Pashupatra astra," Arjuna replied. "I now desire to learn how to use this powerful weapon."
Hearing Arjuna's desire, Lord Shiva said, "I will grant your request. Just near here is a lake full of amrita (nectar). This is where I keep my celestial bow and arrows. Go there and bring them to me."
Lord Krishna and Arjuna then went to the lake, and in the water they saw two snakes spitting fire and poison. They approached those snakes chanting prayers to Lord Shiva. As they came closer, the two snakes turned into a bow and arrow. Arjuna then took the bow and arrow and returned to Lord Shiva. While glancing at the bow, Lord Shiva produced a brahmachary from the sides of his body. That brahmachary, who was bluish in complexion, then took the bow and strung it. Placing his feet properly and chanting the proper hymns to invoke the astra, the brahmachary released the arrow into the lake nearby. After releasing the arrow, he then threw the bow into the lake. Then Lord Shiva called for the bow and arrow and gave it to Arjuna, and also gave him the benediction that he would fulfill his vow. Arjuna and Lord Krishna, fully satisfied with the worship of Lord Shiva, returned to Kurukshetra and to their own tents. Thus through that dream Arjuna learned how to use the weapon owned by Lord Shiva.
When the morning came all the Pandavas rose from their nightly rest and offered their morning prayers. In the presence of all the assembled Kings, Yudhisthira said to Lord Krishna, "O Krishna, relying on You alone, we seek victory and eternal life. You, O Lord, are aware of the loss of our kingdom at the hands of these vile sinners. O Lord of lords, You are compassionate to Your devotees who rely on You for their very existence. O slayer of Madhu, please help Arjuna to realize his vow. O descendant of Vrishni, become the boat that will take us across this vast ocean of the Kauravas. I offer my respectful obeisances unto You who are the eternal Lord, the Supreme Destroyer. O eternal Vishnu, O Hari, O Vaikunthanatha, Narada has described You to be the Supreme Lord, Narayana, who carries the Sarnga bow and who wields the Sudarshana cakra. O Lord of all creatures, please be merciful to us and do not allow Arjuna to enter fire at the end of the day. O Lord, may his vow be fulfilled."
To these prayers, Lord Krishna replied, "O Yudhisthira, in all the three worlds, there is no bowman who compares to Arjuna. He is the possessor of great weapons and wields the prowess of thousands of warriors. Treading over the heads of his enemies, he will certainly fulfill his oath. This very day you will see that sinful person, Jayadratha, laying on the Kurukshetra plain and his soul entering Yamaraja's abode. Today, vultures and jackals will feast on the flesh of his dead body. Even if all the demigods united become Jayadratha's protectors, that ruler of the Sindhus will not live. Dispel all your anxiety and lamentation."
While Lord Krishna and Yudhisthira were speaking, Arjuna came into their presence. Yudhisthira, rising from his seat, embraced Arjuna and smelt his head. He then addressed him, "It is evident from your smiling face that victory awaits you today. With the full blessings of our eternal well wisher, Lord Krishna, I shall see you here at the end of the day with you vows fulfilled."
Arjuna then described to all present his dream of the previous night. He described how Lord Shiva had instructed him to use the Pashupatastra. He also told them that Lord Shiva blessed him with the fulfillment of his desires. Hearing this excellent story, all were struck with wonder and exclaimed, "Excellent! Excellent!" Then with joyous hearts they proceeded to the battlefield to make preparations for the day's battle."