Defeat the Minor Manifestation of Fire, and place the Glowing Ember in the brazier atop the Shrine of Eternal Flame.
The fire sapta is finished. The time has come for you to face the flame. Use the sapta at the shrine and head to the top of the mountain to face the manifestation there. He will not attack until you are ready, but he will realize you are able to see him.
Strike him down swiftly, [player], for he shall only grow in power the longer you take to slay him. Once he is defeated, place his glowing embers within the brazier and light the torch.