In those days Merlin the Druid was the wisest oracle in the land. His powers of prognostication were infallible. He had made many prophetic pronouncements, but the one that concerns this tale was his prediction that Trym Deeptroll, the most fearsome troll in the Black Mountains, would one day emerge from Fan Brycheiniog and come to Camelot where he would destroy the throne room and leave the Round Table in splinters.

Upon hearing Merlin’s prophecy, King Arthur proclaimed that any knight in his service who undertook the quest to vanquish Trym Deeptroll would be showered with accolades and riches for their heroic deeds. And so it was that Sir Brychan rose without hesitation and said, “Sire, Trym Deeptroll has dwelt in my lands of Brycheiniog longer than the memory of man. My allegiance has been pledged to you, Overking, from the day I set foot upon the soil of Wales, and it is for thee that I have defeated the criminals of Southern Wales and set myself a realm under your banner. And while trollkind have been pushed to the depths of the mountains, it is only just that I should turn my efforts downwards to them now that I have cleared the upper world of evil.”
King Arthur, swelled with admiration for this brave and capable knight, spoke saying, “Very well, Sir Brychan, it is fitting that you should undertake this quest as it is within your realm of Brycheiniog that dwells this vile creature who has been shown in Merlin’s vision to be the cause of such calamity.”
Sir Brychan left Camelot and journeyed homeward towards Southern Wales. He arrived at the Black Mountains and made his way to the mighty mountain of Fan Brycheiniog. It had been many years longer than most men’s memory since the trolls had emerged from the depths of the mountain and it took Brychan several days to find a cave that connected to the roots of the old mountain.

Down, down, down, he climbed and crawled until the passageways opened up wider and wider and the troll’s caverns were discovered to be grand and well-tended. Brychan, ever on guard for an attack was soon greeted by the immense troll Trym Deeptroll.
He laughed at Brychan clad from head to toe in his burnished armor and brandishing his shield and sword. “So, Human Knight, you’ve come to hack down Trym Deeptroll? What cause have you for invading my caverns clad for battle? What are my crimes?”
Brychan, poised for deception, cautiously circled and said, “The great oracle Merlin has read the signs of Fate and have divined that you are plotting the ruin of Camelot. So, I ask you, what crimes have King Arthur or the Knights of the Round Table done to warrant such machinations from that foul brain of yours, Beast?”
Trym backed up and sat upon a great bolder. He was seemingly unconcerned about Brychan’s sword or his armored posture of battle.
Trym thought a moment and said, “Brychan mac Anlach, your father was of Ireland, and you are but a youngling, recently arrived in this land. I have been here far longer than you could imagine. When I first came here ages ago, this great mountain was called Bryn Y Hen, the Old Hill. For countless generations of man, I’ve lived beneath the earth and seen these mountains grow. In all this time, I and my brothers and sisters have had little concern for the lives of men. Occasionally our kinds have crossed paths, but we’ve left each other well enough alone to our own, respective realms. Now you come to me with this distressing news of accusations that neither of us seems to have any real cause for justification. Could Fate really be so stacked against us?”

At this, Brychan was suddenly perplexed. “I know not the nature of Fate’s methods. But I do know that Merlin is the greatest of his order. He has made many famous prophecies and every last one of them has come to pass. If he has seen the sign that you will cause harm to our great kingdom, then I must prevent that by whatever skill I can bring upon you.”
Trym placed his massive head in his hands and thought some more on the matter and then he said, “Suppose that Merlin were only predicting one possible outcome that might come to pass. For, right now, I have no intention of doing any harm to any man. But suppose you were urged to come here and attack me, and suppose, for the sake of understanding this, that you provoked me into anger. Maybe I hurt you or even kill you and take out my vengeance by attacking Camelot. What purpose do you serve in making this happen?”
“To the contrary, Troll,” Brychan exclaimed. “I have come here to ensure that you are slain so that you may not cause this vengeance!”
“Oh, ho!” Trym said holding a finger up. “So, you do believe that Fate can be thus thwarted, and that Merlin’s prognostication might only be a caution?”
Now Brychan was thoroughly cornered in his own reason. He relaxed his stance and rested his hands upon his sword pommel thinking the matter over. “Yes,” he said after a few moments thought, “I suppose my entire quest was an attempt to prevent Merlin’s vision. But what should I have done otherwise? After all, it was King Arthur’s call to arms that led to this journey to stop you.”
Trym chuckled and said, “Well, I’m glad you’ve come around to my way of seeing it; however, I would propose a more attractive solution that will prevent your or my deaths in this matter.”
“What did you have mind?”
“You’re no doubt familiar with the powers of trolls?”
Brychan was indeed familiar with the nature of trollkind. “Yes, I know that trolls have the ability to regenerate. If I were to lop off your mighty arm, you’d soon grow it right back. I’d have to sever your head from your body and burn the corpse to truly kill you.”
“Right, and how about our weaknesses?”
“Well, I know you prefer the dark as the sun will slowly turn your skin to a stone-like hardness. And I also know that the bite of well-forged iron also causes your skin to react in a similar way, although not quite so bad as direct sunlight.”
“Ah, not just the bite of iron, but even the touch of iron to the skin is a curse to the trolls.”
“And what does this have to do with matter, Lord Deeptroll?”
“I propose to bend the knee, as you men say, and pay homage to King Arthur; beg his forgiveness for any ill will that he might suspect so that he’ll see I’m not remotely concerned with harming anyone above ground. On the contrary, I would have him see me as a loyal subject, ready to defend rather than harm. But to do this, I’d warrant you’d want me reduced to a defenseless and vulnerable prisoner.”

And so it came to pass that Trym and Brychan stood before King Arthur. Trym had been transported inside of a specially made cage aboard a wagon that was more akin to an iron box than a cage.
Brychan explained to the King the entire conversation he and the troll had had and how Trym now wished to bend the knee to the King of Camelot and pledge his fealty.
King Arthur called for Merlin to attend the great hall and said to the old Druid, “Well, Merlin, what do you make of such attempts to thwart your prophecies? Is it possible that what you’ve seen in visions is but a possible outcome?”
Merlin, ever the enigma, said, “Sire, I have never seen a vision that didn’t come to pass. The prophecies aren’t something I interpret about possible futures; they are visions as clear as if they had happened from a memory of things already transpired. All I can tell you is what I observed in the vision. Trym Deeptroll was raging as a berserker of the Danes as he tore asunder the Round Table and the throne.”
After some deliberation and hearing all of the arguments for and against – even hearing the same and similar arguments from Trym as he had used on Brychan – King Arthur finally declared his judgement.

“I cannot, in my best conscious, jeopardize Merlin’s keen prognostication abilities. For, he has never failed to clearly divine the future when he has proclaimed a vision has beset him. Trym Deeptroll, it is with heavy heart that I say to you that I cannot free you and accept your fealty and then in turn let you go free. I do not trust your motive given Merlin’s vision. I’m afraid that you must be held prisoner until the time of your execution.”
Upon hearing this, Trym began to below from within his prison. His anger was vented in all manner of vile curses. And while Brychan had rightly known many of the abilities of trolls, one ability had evaded his knowledge. Trolls have the ability to burrow through earth and rock as easily as a crab burrows through sand. The iron box was truly impossible for the troll to escape, however, the box rested upon a stone slab and it was clear through the floor that Trym now made his escape beneath the castle’s foundation.
Hearing the cursing and rumbling from within the iron box, King Arthur and all the knights present in the great throne room all readied themselves for battle. Shortly thereafter, the box grew strangely quiet and for many minutes everyone waited and exchanged worried looks. Finally, one brave knight cautioned to peek through and slot in the cage and exclaimed, “Sire, it is empty!”
Two days passed with not any sign of Trym Deeptroll. King Arthur called for several brave knights to venture into the tunnel burrowed by the troll, but they ventured so cautiously that Trym had long disappeared into other natural caverns and become hopelessly untraceable.
Then, near midnight of the third night, a great commotion woke the entire castle and brought everyone to congregate in the great hall. They beheld, of course, the great troll king, Trym Deeptroll, in the final throes of his rage. He had emerged from the ground right into the throne room and immediately commenced thrashing and rending the legendary Round Table and the stone-wrought high throne until all were but splinters and rubble. Just as everyone descended upon the great hall, Trym disappeared once again into the ground, never to be seen again by the men of the upper world.
It was much later, after the many craftsmen of Camelot had rebuilt a much more impressive and sturdier throne, and after a more ornate and awe-inspiring Round Table had been unveiled to seat those fabled knights, that King Arthur asked Merlin the question. “Do you think I made the right judgment, my old mentor? What would have happened if I had shown the troll mercy and simply let him go back to his lair in peace?”
Merlin thought a moment and said, “Then I’m sure I would have seen a different vision, Sire.”
