Lord Shiva spoke - "So what should I call you? Should I call you by your current name Reaper or should I call you by your ancient name O General of the Asura Army "Asur Raktabija". Boom!
Reaper was dumbfounded!
He thought what the hell is Lord Shiva speaking; Me what, Raktabija? How in the world is this possible?
Reaper was so confused and didn't know how to reply to what Lord Shiva said!
Well, his confusion was also justified because the name Lord Shiva spoke was actually the name of a terrifying ancient demon.
So who was Raktabija?
Well according to Hindu mythology during Dvapara yug there were 2 Asur(demon) Brothers known as "Sumbha and Nisumbha"!
They want to rule 3 realms known as "Swarg Lok" where gods and goddesses live (heavens); "Prithvi Lok" where humans live(earth) and "Patal Lok" where Daanavs, Daityas, and Asuras live( netherworld).
(Well according to ancient Hindu scriptures there are many other realms beside them there total of 14 realms; "6 realms are above the earth( earth is 7th realm) and other 7 realms are below the earth" These 14 realms are also known as materialistic Realms and there is also 15th realm which is called spiritual realm in which Lord Vishnu live)
So Sumbha and Nisumbha want to rule these 3 realms because; until the period of Dvapar yug people of these 3 realms have permission from Supreme gods that they can travel between these 3 realms.
So Sumbha and Nisumbha prayed for a thousand years to The Supreme God Brahma to get a Boon (blessing) from Lord Brahma.
In the end, Lord Brahma becomes happy with their devotion and agrees to give them a boon.
So to win 3 realms Sumbha and Nisumbha asked Lord Brahma boon of immortality but they were refused by Lord Brahma because granting such a boon is against the laws of nature; Lord Brahma told them to ask for anything else!
So they both thought why should they not ask for something which literally can make them invincible? So as Boon both brothers asked if they were going to get defeated in the future then only a woman, can defeat them and she should be unmarried and she should be someone who doesn't get birth from the womb of another woman.
They thought that if Male gods couldn't defeat them and how could a female god (goddess) can defeat them? And the women who is supposed to defeat them, is not going to get birth in the first place than who will defeat them? Well, this arrogance later became the downfall of both brothers.
So after getting Boom from Lord Bharma; they attacked and won all 3 realms. After winning 3 realms, they started doing bad deeds and started tormenting people.
After knowing that Gods couldn't defeat both brothers and his Asur army, then all gods prayed to Goddess Parvati, who was also the wife of Lord Shiva. Goddess Parvati is also known as Adi Shakti or Mahadevi because she holds Half powers of Lord Shiva and is also known as half Supreme Goddess.
Once Goddess Parvati had promised to gods that if someday they needed help with anything then she would help them!
So gods prayed to Goddess Parvati for help and to help gods; Goddess Parvati gave birth to "Mata Durga"(Goddess Durga), Goddess Kali, and Goddess Chandika with her divine powers.
These 3 goddesses were unmarried and didn't get birth from the womb of another woman instead, they are avatars of Goddess Parvati which she created using her divine powers, so they are the solution for the Boon of Sumbha and Nisumbha.
So these 3 goddesses attacked Asur's army and annihilated a huge amount of Asurs and also killed many generals of Asur's Army.
Then both brothers send most powerful and terrifying general of their army; who had made many gods run for their lives and made them feel great despair.
He was Asur General Raktabija! To kill him was nearly impossible for the gods because he had also gotten a boon from Lord Bramha that whenever, drops of his blood fell on the ground, a new Raktabijas would arise from the blood and fight the enemies. Each of these Raktabijas would also be like the others in the matter of strength, form, and weapons.
As many drops of blood fell from his body, so many asuras came into being and they too fought with the Mother-goddesses.
So goddesses thought of a new plan to kill Raktabija!
Chandika laughed and said to Kali, "O Chamunda, keep your mouth wide open while I attack the mighty asura and as I do so, quickly drink all the blood before it falls to the ground".
Hit by a multitude of weapons the Great Asura lost all his blood and before his blood could touch the ground it was drunk by goddess Kali in the air and finally, Raktabija eventually fell on the ground and died.
All gods cheered on his death and when Sumbha and Nisumbha found out about Raktabija's death, they also found it impossible and unbelievable! This type of great confidence they had in Raktabija.
So after Raktabija's death, Sumbha and Nisumbha fought with goddesses and they both were slain by Goddess Chandika and Goddess Durga.
In the whole war, Goddesses found Raktabija most difficult to kill, after his death even Asur kings Sumbha and Nisumbha were easily slain by them.
Peace was again restored in 3 realms, after their death and all gods came and thanked and prayed to Goddess Parvati for her help.