"Kalkin, final avatar (incarnation) of the Hindu god Vishnu, who is yet to appear. At the end of the present Kali yuga (age), when virtue and dharma have disappeared and the world is ruled by the unjust, Kalkin will appear to destroy the wicked and to usher in a new age. He will be seated on a white horse with a naked sword in his hand, blazing like a comet."
https://www.britannica.com/topic/Kalkin
"Kalki’s primary mission is to defeat the demon Kali, who symbolizes the negative traits and forces that dominate Kali Yuga. Kalki will establish Dharma and inaugurate the next age, Satya Yuga, characterized by truth, virtue, and righteousness."
https://medium.com/@vedicstorymarketing/story-of-kalki-avatar-the-10th-avatar-of-lord-vishnu-a25b9d8d543e
"A harbinger of the apocalypse, it is believed that Kalki will bring about the destruction of the world when mankind has completely abandoned religion, “when nothing is known of the techniques of sacrifice, even by word.”"
https://www.ancient-origins.net/myths-legends/when-kalki-destroyer-descends-greed-corruption-war-destruction-and-apocalypse-006545#google_vignette
"According to Puranas, Kalki, also known as Kalkin or Karki is the upcoming and last avatar of Lord Vishnu. He will recycle time by ending the Kaliyug and re-initiating the Satya Yuga. He will be the one who will rejuvenate existence by ending the Adharma and ushering in the Satya Yuga. However, the predictions made about the Kalki avatar are inconsistent among the Puranic texts. For example, he is just an invisible force destroying evil in some texts, while an actual person who kills those who persecute others in other texts, and some texts portrayed him as someone leading an army of Naga warriors to eliminate Adharma from the world as per Kalki predictions. Furthermore, his story has been compared to the concepts of Messiah, Apocalypse, Frashokereti, and Maitreya in other religions."
https://www.ganeshaspeaks.com/predictions/astrology/about-kalki-avatar/
"Kalki is the only avatar of Vishnu that is yet to be born which is mentioned in Srimad Bhagavatam, Vishnu Purana, Mahabharata, Matsya Purana, and Kalki Purana. He will end all evil by defeating the demon Kali and starting a new Satyayuga or Kalkiyuga.
Asura Kali is all the negative emotions and elements personified into one."
https://vedicfeed.com/kalki-avatar/#google_vignette