Ragnarok, Final Battle Between Siblings

"Mm, that's right!" Loki murmured.

After thousands of years, he still had the heart of a king. For some reason, he felt a sense of responsibility as a king.

Decisively walking over to the stone platform where the Aether was, Loki grabbed it and stuffed it into his chest.

Then, he carried the rusty prong to another stone platform.

There was a brazier on the platform. There was no fuel inside, but a fire was burning fiercely.

Loki stared at it for a moment, before he finally made up his mind. He threw the prong into it and ran.

That was because the fire in the brazier was the Eternal Flame, and the 'prong' was actually the crown of the Fire Demon Surtur.

The complete form of Surtur was actually the Eternal Flame + the Fire Crown.

According to Odin's prophecy of Ragnarok, it was the complete form of Surtur brandishing his flaming greatsword that would completely destroy Asgard.