The Consistency Of Trolls

As the sun fell west the shadow of the world's horizon crept forth in the dusky sky; it yawned across lakes, rivers, and plains, and the shadows of trees and rocks lengthened. Deep in the Ettendales the shadows now rose, and sunk the wheels of a great wagon parked some distance from a mountain cave. The wagon was known as The Mother, chief weapon of Jötunvinur, the Troll-hunter. He himself was stood upon the seat eating from an apple. He seemed to be waiting for something.
Suddenly a pair of gleaming eyes kindled in the depths of the cave; they were two golden moons in a stormy sky, full of malice and wroth. The eyes of a troll. They now watched Jötunvinur intently.
Madness men called it, to hunt trolls at the day's end; for their skin could turn steel and shatter iron, but only the enchantment of the sun might undo them. Better to hunt at foredawn, they said, where the sun will rise and ward off all evils.
But here Jötunvinur stood as the sun dipped, against all better judgement. He leaned against a bulky object in his wagon that was covered in hide tarp, and with an air of indifference he took another bite from his apple.
'I always wondered,' he spoke out with his mouth full, 'what type of rock do Etten-trolls turn into. Marble? Slate? Quartzite maybe?'
A slow rumbling growl issued from the cave, and the two moons narrowed.
Jötunvinur looked down with his one good eye in search of a choice bite.
'The thing is,' he went on, 'I admire trolls. Really I do. You get all types in the world: stone; wood; cave; snow- but you all have one thing in common. You're consistent.' He waved his apple around in gesture and added: 'consistently stupid.'
The gleaming eyes of the cave now became slits of hate, but Jötunvinur burst into husky laughter. Slowly the horizon's shadow crept up until all but his laughing face was submerged. And then it happened.
Suddenly a great bellow issued from the mouth of the cave, and out charged an enormous shape with thunderous abandon. It made straight for Jötunvinur and his wagon. Trees were knocked down in its wake as if they were reeds blown aside in a hurricane, and the earth trembled with each lumbering footfall.
Jötunvinur moved quickly. He stuffed the apple in his mouth and yanked the tarp away to unveil his arsenal: 
There upon the wagon was erected a large disk, mounted upon a pedestal. Wrought from bronze and shaped into the image of a flaming sun, in its make it carried the lore of dwarven craftsmanship. The years had weathered most of the contraption, but the front face was unblemished; for it had been burnished so clearly that it could reflect light with a keen brilliance.
This was indeed a dwarvish mirror, an ancient device of Durin's Folk used at the height of their power. In years of old they illuminated great kingdom halls beneath the mountains, where now only darkness dwells; but in these times such items had been salvaged from better days and repurposed for lesser means.
Sharply he swung the mirror, and in a flash of flame the disk caught the last light of day. The reflection shone out like a spear, the shadows sprang aside, and the sun's ray leapt upon the hurtling troll. It's monstrosity was illuminated for all to see.
It had been too eager to assail Jötunvinur; too easily goaded from its hateful pit in the mountain side, and did not reckon on the cunning of an old man to bring sunlight from beyond the horizon.
Now Its face contorted with hideous rage, and its large mottled hand outstretched to seize him. But even as it tried, the troll's rampage was arrested with a painful shudder, for the enchantment of the sun was instant: flesh was scorched to grey stone wherever the beam of light seared, and from its fingers down to its toes wound the curse of day. Its eyes were the last to change, and then they were extinguished.
In a defiant roar the troll's ruin blared across the mountain side, and it's echo caused flocks of birds to flee from the tree tops. Then a great silence followed. The sun vanished behind the horizon with a wink; the mirror dimmed, and forever more the troll stood as a statue of frozen wrath.
Jötunvinur stirred, quite unperturbed, and took the apple out of his mouth. He leaned forward to squint at the stone fingers that groped a mere inch from his face. He sniffed before licking the foremost digit. 
'Limestone,' he muttered.