“Just at that moment all the lights in the cavern went out, and the great fire went off, ‘poof’, into a tower of blue glowing smoke, right up to the roof, that scattered piercing white sparks all among the goblins. […] the smoke that now fell from the roof made the air too thick for even their eyes to see through. Suddenly a sword flashed in its own light. Bilbo saw it go right through the Great Goblin as he stood dumbfounded in the middle of his rage. He fell dead, and the goblin soldiers fled before the sword shrieking into the darkness. The sword went back into its sheath. “Follow me quick!” said a voice fierce and quiet…”
The Hobbit, or There and Back Again by J. R. R. Tolkein