This is Mother Kali, one of the millions of deities in Hinduism. She is the Aathishakti (The Mother Divine in any fierce form as 'Kali,' it's a kind of short-hand that inclues Durga, Chandika, Mahishasoora Mardini and other fierce forms of Mother.
Other names for Kali include: Kali Ma, The Dark Goddess, Dark Mother, Kalika, The Black Goddess, Kali the Destroyer, Consort of Shiva, Dancing Lady of Death.it's also part of Shiva's nature, to give boons to rakshasas, even though those boons usually wind up threatening the whole creation. Shiva is 'bolo-shankara', purely innocent and open-hearted. generous to a fault.
Notice she holds weapons and a severed head and a bowl to catch the blood in. Her jewelry is dismembered bodies, her necklace severed heads, her skirt is made of severed arms from the devils. According to Hinduism, within the human body, Kali is the Kundalini, the "Serpent Power", the key to liberation-if properly controlled. If not, the Kundalini will do great mental and bodily harm.
Why the Divine Mother came this way? Read this friends...and please change ur perception about Her!
Once upon a time, a demon (again, he has many names depending on what region in India the story is told, like Mahesasura, Raktabija, etc.) spent a great deal of time and effort worshipping Shiva, in deep meditation. the demons, or rakshasas, are actually great meditators, and are very good at doing austerities to win the attention and the love of Lord Shiva. it's a curious point that the rakshasas often have more powerful souls, at the pure level, than the avataras do. it's a mystery as to why this is, since at some point the rakshasas make some fatal (and usually highly selfish) blunder and lose all the fruits of their meditation in some stupid way. but that's nature.
Anyway, this rakshasa did his austerities, got the darshan of Lord Shiva (got to see Shiva, physically, in a super-natural form) and Shiva was so pleased with the hard meditations the rakshasa had done, he granted the demon whatever boon he wanted. the clever demon asked for the boon that every time his blood hit the ground from a wound, a THOUSAND more Mahesasuras would spring up from that blood. essentially, he was making himself invincible, immortal. Shiva granted the boon.Immediately the demon came attacking the gods, killing and harming many of the divine beings in creation. they were powerless against him, even though they had fantastical weapons -- because Shiva's boon was in place and every time Mahesasura was wounded and his blood hit the ground, a thousand more of him would spring up, ready to fight.
The level of destruction that he threatened to carry out in creation was too much for any of the devatas (the gods) to fight. they couldn't do it. no one was powerful enough to stop the rakshasa, so they all came together, all the gods (like Brahma, Vishnu, Shiva and the OTHER millions of divine forms in the pantheon), all the goddesses, (like Saraswati, Laxmi, Parvati and the others), all the rishis (the great creator-sages), all the angels, all the divine beings in this creation, every last one of them. they united and merged together and made ONE form.
That one form, the highest divinity form of Mother Divine, is known as Maha Kali. SHE came into creation and killed that rakshasa by a simple method -- every time She wounded him, and his blood was starting to drip, She would extend her humongous tongue and eat his blood before it ever had a chance to hit the ground!
This is why there are so many many misunderstandings about Maha Kali -- many people have the mistaken impression that because She is so fierce, so hideous-looking (wild-eyed, long bloody tongue hanging out of Her mouth, fangs dripping blood), She is some kind of demonic force in creation.
the truth is that She is the highest divine form of the Mother energy -- She is the convergence of ALL the divine beings in Her one form. it takes that fierce an expression of the high positivity to defeat the highest negativity.
It's also part of Shiva's nature, to give boons to rakshasas, even though those boons usually wind up threatening the whole creation. Shiva is 'bolo-shankara', purely innocent and open-hearted. generous to a fault.