The Vow
Karna worshipped the sun every morning. During those prayers, he was known never to refuse any request. This was his dharma, his public vow, his identity.
Indra knew this. He knew that if Karna died wearing his natural divine armor, the Pandavas could not win the war. So he would go as a Brahmin and ask for the armor during morning prayers.
Surya, the sun god, warned Karna every night in dreams. "Indra will come. Refuse him." Every morning Karna rose and stood before the sun and knew he could not refuse.
The Morning
Indra came. A thin old Brahmin, poorly dressed, standing humbly at the door.
He asked for the kavach and kundala.
Karna smiled. He had been waiting. He knew the face.
He said: "I know who you are. And I know what you have come for. And I know what it will cost me. Take it."
He peeled the armor from his skin, bleeding. He handed it over. He removed the earrings.
Indra, shamed, gave him the Shakti weapon in exchange — one unstoppable lance.
What Was Left
Karna went to war without his natural protection. He had one divine weapon that could not miss.
He used it — not on Arjuna as intended, but on Ghatotkacha, to save Duryodhana in a critical moment. It was gone.
He fought the final battle with no armor, no divine weapon, no support from his charioteer Shalya. And he died — having given everything away, holding nothing back.