I want to know the references in puranas for Shakambari devi. Full context of the reasons for Devi taking this Avatara and any asura vadha done as part of it(i.e if it is taken for killing asuras).
Shakumbhari Devi is said to be an aspect of Goddess Durga. Shakambhari means She who nourishes by bringing (ambhari) vegetation or herbs (shaaka). She is also called Banashankari (वनशंकरि) or the Goddess of the forest. She is hailed as Shataakshi (शताक्षी) because She has one hundred eyes.
Shakambari devi is mentioned in Mahabharata -Book 3: Vana Parva - Tirtha-yatra Parva - SECTION LXXXIV
ततो गच्छेत राजेन्द्र देव्या: स्थानं सुदुर्लभम |
शाकम्भरीति विख्याता त्रिषु लोकेषु विश्रुता || MB 3.84.13 ||
दिव्यं वर्षसहस्त्रं हि शाकेन किल सुव्रता |
आहारं स कृतवती मासि मासि नराधिपा ||MB 3.84.15 ||
ऋषयोSभ्यागतास्तत्र देव्या भक्ता तपोधना: |
अथिथ्यं च कृतं तेषा शाकेन किल भारत ||MB 3.84.15 ||
P. 184 - One should next proceed, O king, to the excellent spot of the Goddess celebrated over the three worlds by the name of Sakamvari. There, for the space of a thousand celestial years, she of excellent vows, month after month, had subsisted upon herbs, O king of men! And attracted by their reverence for the Goddess, many Rishis with wealth of asceticism, came thither, O Bharata. and were entertained by her with herbs. And it is for this that they bestowed on her the name of Sakamvari.
The Story Of Shakambhari Devi is narrated in Skandha 7 - Chapter - 28 of Devi Bhagavata Purana - On the glory of the Śatakṣi Devī.
Here are excerpts from the purana -:
In olden times, there was a great Dānava named Durgama: he was very cruel. He, the the son of Ruru, was born in the family of Hiraṇyākṣa.
Once he thought
The Vedas is the strength of the Devas; if the Vedas be destroyed, the Devas also would be destroyed. Thus it is advisable to destroy the Vedas. He began to meditate Brahmā .
He practised hard tapasyā for one thousand years and the Devas and the Asuras and all the Lokas were agitated by the power of his Tejas (fiery lustre). Then the Bhagavān, the four-faced Brahmā, became pleased with him and mounting on his carrier, the Swan came up there to grant him the boon. Hearing thus, the Demon got up from his Samādhi and worshipping Him duly, said :-- “O Lord of the Devas! Give me all theVedas. O Maheśvara! Let all the Vedic Mantrams, that are found in the three worlds, with the Brāhmaṇas and the Devas, come to me and give me such strength as would enable me to conquer the Devas.” Hearing this, the God Brahmā, the author of the four Vedas, replied, “Let it be as you wish,” and went away. From that time, the Brāhmaṇas forgot all about the Vedas. So bathing, Sandhyā, daily Homas, Śrāddha, sacrifice, and Japam and other rites and performances, all became extinct.
Then a cry of universal distress arose on the surface of this wide earth; the Brāhmiṇs began to say to each other :-- “How has this happened! How has this come to pass! Now what are we to do? Where the Vedas have disappeared.” Thus when great calamities befell on the earth, the Devas became gradually weaker and weaker, not getting their share of the sacrificial Havis. At this time, that Demon invested the city of Amarāvatī. And the Devas, not being able to fight with the Asura, of a thunder-like body fled to various directions. They took refuge in the caves of the mountain Sumeru and the inaccessible passes of the mountain and began to meditate on the Highest Force, the Great Goddess. When the body of the Brāhmaṇas thus praised and chanted the hymns of Maheśvarī,
She created innumerable eyes within Her body and became visible. Her colour was dark-blue (colour of the fourth dimension, space) like heaps of collyrium (eye-paint); eyes like the blue lotuses and expanded; breasts hard, regularly elevated round and so fleshy that they touched each other; four handed; with Her right hand, holding arrows; on the under hand holding lotus; on the upper-left hand holding a great bow and on the lower hand, carrying vegetables, fruits, flower and roots with abundance of juice, destroying hunger, thirst and fever. She was the Essence of all Beauty, lovely, luminous like the thousand Suns, and the ocean of mercy. That Upholder of the Universe, showed Her form and began to shed waters from Her eyes. For nine nights continuously, the heavy rains poured down out of the waters flowing from Her eyes. Seeing the misery of all the people, out of [Page 690] pity, She showered incessantly tears from Her eyes; and all the people and medicines were satisfied. What more than this, out of those tears, the rivers began to flow. The
As Thou, O Devī! hast innumerable eyes only for our welfare and peace, therefore Thou wilt be called henceforth by the name “Śatākṣī.” O Mother! We are very much hungry; so we have no power to chant hymns to Thee; therefore, O Maheśvarī? Shew mercy on us and deliver to us our Vedas.
46-68. Vyāsa said :-- O King! Hearing these words of the Devas and the Brāhmiṇs, the Auspicious One gave them the vegetables, delicious fruits and roots to them that were on Her Hand, for their eating. After She was prayed, She gave to men sufficient quantity of various articles of juicy food and to the beasts, grass, etc., until new crops came out. O King, from that day She became famous by the name of Śākambharī
When the fatal eleventh day arrive the Dānava, wearing red clothes on his waist, red garlands on his neck and annointing his body all over with red sandal paste, celebrated a very grand festivity and mounted on his chariot and went out to fight. With the strenuous effort, he defeated all the Śaktis and placed his chariot before the Devī. Then a terrible fight ensued for two Praharas (six hours). The hearts of all shivered with horror. At this time, the Devī shot fifteen very awful arrows at the Dānava. His four horses (Vāhanas) were pierced by Her four arrows; the charioteer was pierced by one arrow; his two eyes were pierced by two arrows; his arms by two arrows, his flag by one arrow and his heart was pierced by five arrows. He then left his body before the Devī, vomitting blood. The vital spirit, the luminous counterpart, emitting from his body, merged in the space-like body of the Devī. The three worlds, then, assumed a peaceful appearance when that greatly powerful Dānava was killed. Then Hari, Hara, Brahmā and the other Devas began to praise and chant hymns to the World Mother with great devotion and in voices, choked with feelings.
So the reason for devi to take this avatara is to save the universe and to kill Daemon Durgama. Rescue the vedas and Brahmanas (who are the keeper) as well as all the people from thirst and hunger , and to again make this universe a peaceful place.