I'm looking for a story in which the hero's enemy (or rival) takes most of the heat protectant salve and spreads it on his body like a golden skin, so that the enemy can get through the fiery heat undamaged. The hero then takes the pitiful remainder and applies it very thinly, but enough to get through also. It's an ordeal for the hero to get through the heat, and the fire burns away the salve and hurts, but the hero makes it through. The enemy, though, has applied it too thickly and becomes petrified as the unburned salve that he's wearing solidifies into a hard shell once he's out of the fire. It could be a short story or a scene in a larger novel; it is not the climactic twist, though, the hero continues onwards.