After being betrayed during the apocalypse, I became a raid boss

One day the world will die and plunge into darkness. Then the human spirit will understand what death is. And then all the celestials will want to escape, and people will have to survive. So it was said in the ancient legends of our world. However, when all the celestials fled, and people lost all hope, another celestial came to humanity, but all he could do was delay the death of this world, because he himself could not interfere in the affairs of mortals and save this world. People themselves had to eradicate the villain who cursed this world to death. But something went wrong...