In the Arjuna‑vanavasa Parva, there is a tale of celestial apsaras, Varga and her friends, cursed into being crocodiles by a brahmana. Arjuna delivers them from their curse and hence are transformed to their original self,“Hearing what had happened the Rishi said, 'In the low-lands bordering on the southern ocean, there are five regions of sacred water. They are delightful and eminently holy. Go ye thither without delay. That tiger among men, Dhananjaya, the son of Pandu of pure soul, will soon deliver you, without doubt, from this sad plight.' O hero, hearing the Rishi's words, all of us came hither. O sinless one, true it is that I have today been delivered by thee. But those four friends of mine are still within the other waters here. O hero, do a good deed by delivering them also.'
"Vaisampayana continued, 'Then, O monarch, that foremost of the Pandavas, endued with great prowess, cheerfully delivered all of them from that curse. Rising from the waters they all regained their own forms. Those Apsaras then, O king, all looked as before. Freeing those sacred waters (from the danger for which they had been notorious), and giving the Apsaras leave to go where they chose”,
SECTION CCXIX Arjuna-vanavasa Parva K M Ganguli’s Mahabharat
Slaughter of Gandharvas
In Vana Parva, there is an episode where Arjuna fights the Gandharvas, celestial beings, in battle and uses several astra (celestial weapons) to great effect. He traps them in arrows, cuts off their weapons, and uses powerful divine astras to check their attack and then counterattacks.
“Then Arjuna of the Kuru race shot his well-known weapons called Sthunakarna, Indrajala, Saura, Agneya and Saumya. And the Gandharvas consumed by the fiery weapons of Kunti's son, began to suffer heavily, like the sons of Diti, while being scorched by Sakra's thunder-bolt. And when they attacked Arjuna from above, they were checked by his net of arrows. And while they attacked him from all sides on the surface of the earth, they were checked by his crescent-shaped arrows. And beholding the Gandharvas put in fear by Kunti's son, Chitrasena rushed, O Bharata, at Dhananjaya, armed with a mace. And as the king of the Gandharvas was rushing at Arjuna from above with that mace in hand, the latter cut with his arrows that mace wholly made of iron into seven pieces. And beholding that mace of his cut into many pieces by Arjuna of great activity, with his arrows, Chitrasena, by means of his science, concealed himself from the view of the Pandava and began to fight with him.”
SECTION CCXLIII Vana Parva K M Ganguli’s Mahabharat
Another one less remarked upon is during the Swayamvara of Draupadi. Arjuna fights Karna. Their duel is notable for how fiercely they match each other, and how Arjuna’s strength of arms, energy, and stamina are praised even by Karna.
“Then the illustrious Arjuna beholding Karna, the son of Vikartana (Surya), advancing towards him, drew his tough bow and pieced him with his sharp arrows. And the impetus of those whetted arrows furnished with fierce energy made Radheya (Karna) faint. Recovering consciousness Karna attacked Arjuna with greater care than before. Then Karna and Arjuna, both foremost of victorious warriors, desirous of vanquishing each other, fought madly on. And such was the lightness of hand they both displayed that (each enveloped by the other's shower of arrows) they both became invisible (unto the spectators of their encounter). 'Behold the strength of my arms.'--'Mark, how I have counteracted that feat,'--those were the words--intelligible to heroes alone--in which they addressed each other. And incensed at finding the strength and energy of Arjuna's arms unequalled on the earth, Karna, the son of Surya, fought with greater vigour. And parrying all those impetuous arrows shot at him by Arjuna, Karna sent up a loud shout. And this feat of his was applauded by all the warriors. Then addressing his antagonist, Karna said, 'O thou foremost of Brahmanas, I am gratified to observe the energy of thy arms that knoweth no relaxation in battle and thy weapons themselves fit for achieving victory. Art thou the embodiment of the science of weapons, or art thou Rama that best of Brahmanas, or Indra himself, or Indra's younger brother Vishnu called also Achyuta, who for disguising himself hath assumed the form of a Brahmana and mustering such energy of arms fighteth with me? No other person except the husband himself of Sachi or Kiriti, the son of Pandu, is capable of fighting with me when I am angry on the field of battle.' Then hearing those words of his, Phalguna replied, saying, 'O Karna, I am neither the science of arms (personified), nor Rama endued with superhuman powers. I am only a Brahmana who is the foremost of all warriors and all wielders of weapons. By the grace of my preceptor I have become accomplished in the Brahma and the Paurandara weapons. I am here to vanquish thee in battle. Therefore, O hero, wait a little.'
"Vaisampayana continued, 'Thus addressed (by Arjuna), Karna the adopted son of Radha desisted from the fight, for that mighty chariot-fighter thought that Brahma energy is ever invincible.”
SECTION CLXLII Swayamvara Parva K M Ganguli’s mahabharat
Indra tells Arjuna that he had acquired invincible prowess. He challenges him to slay the Nivatakavachas, the demons who lived in the womb of the ocean. That would be his guru dakshina,
“Nothing is there in the three worlds that is not in your power (to achieve) My enemies, those Danavas, named, Nivata-Kavacas dwell in the womb of the ocean. And they number thirty million and are notorious, and all of equal forms and strength and splendour. Do you slay them there, O Kuntis son; and that will be your preceptor’s fee.”
Section CLXVII : Tirtha-yatra Parva K M Ganguli’s Mahabharat
Arjun not only annihilates the invincible demons but also destroys their city,
“Thereupon, O Bharata, in this matter the Lord commanded (Indra), saying, 'O slayer of foes, in another body, even thou shalt be (the destroyer of the Danavas).' Then, in order to slaughter them, Sakra rendered unto thee those weapons. The gods had been unable to slay these, who have been slain by thee. O Bharata, in the fullness of time, hadst thou come hither, in order to destroy them and thou hast done so. O foremost of men, with the object that the demons might be killed, Mahendra had conferred on thee the excellent prime energy of these weapons.'
"Arjuna continued, 'After having destroyed the Danavas, and also subdued that city, with Matali I again went to that abode of the celestials.'"
SECTION CLXXI Tirtha-yatra Parva K M Ganguli’s Mahabharat
In the Karna Parva, Arjuna slays younger brother of Sudakshina of the Kamboja tribe,
“Repairing to that further wing which was protected by the Kambojas, Partha began to grind it forcibly with his arrows like Vasava grinding the Danavas. With broad-headed arrows he began to quickly cut off the arms, with weapons in grasp, and also the heads of foes longing to slay him. Deprived of diverse limbs, and of weapons, they began to fall down on the Earth, like trees of many boughs broken by a hurricane. While he was engaged in thus slaughtering elephants and steeds and car-warriors and foot-soldiers, the younger brother of Sudakshina (the chief of the Kambojas) began to pour showers of arrows on him. With a couple of crescent-shaped arrows, Arjuna cut off the two arms, looking like spiked maces, of his striking assailant, and then his head graced with a face as beautiful as the full moon, with a razor-headed arrow. Deprived of life, he fell down from his vehicle, his body bathed in blood, like the thunder-riven summit of a mountain of red arsenic. Indeed, people saw the tall and exceedingly handsome younger brother of Sudakshina, the chief of the Kambojas, of eyes resembling lotus petals, slain and fall down like a column of gold or like a summit of the golden Sumeru. Then commenced a battle there once more that was fierce and exceedingly wonderful. The condition of the struggling combatants varied repeatedly. Each slain with a single arrow, and combatants of the Kamboja, the Yavana, and the Saka races, fell down bathed in blood, upon which the whole field of battle became one expanse of red, O monarch”.
Section 56 Karna Parva K M Ganguli’s Mahabharat
While in exile, Arjuna and Kirata (a disguised Lord Shiva) combat. Totally in awe of the Pandav’s skill, Lord Shiva bestows the Pashupata weapon on him.