I normally try to stray away from Planeswalkers in my Duel Decks. I feel like they enforce to much of a limit of the decks you can build. However, I really like Koth, and have wanted to do a duel deck with him for a while. But, who could offer an interesting match-up with Koth? After much debate, I came up with Ashiok, and a plot that could explain why both parties don't use as many spells from their home planes to create this duel. So, without further adieu, this is Koth Vs Ashiok. Enjoy!
Ashiok: http://www.mtgvault.com/ciaranmadgrin/decks/duel-deck-ashiok-vs-koth/
Plot:
Adrenaline pumped through Koth's veins as he ran. The phyrexians were chasing him, so close to catching one of the last survivors of the invasion. Koth had barely any energy left to fight, he'd been fighting off these monstrosities all day, and now the odds were stacked too high against him. Another metallic freak jumped at him, and Koth slamming a boulder with some quick geomancy into the Phyrexian. He couldn't keep running all day, and he knew this was getting too close. So, Koth started to focus his remaining energy. He knew the only escape was to planeswalk. So, he gathered as much of his reserves as possible, pushing his body to all of his physical limits. Suddenly, the planes tore slightly for him, and he escaped, if only barely.
When Koth finally came back to his sense, he found himself in a cave. Koth, picking himself up slowly, began studying as much as he could about the cave. Every inch of stone was analyzed, Koth trying to figure out how much mana it would take to split the earth so he could get outside and find out which plane he was on. As he gathered information, a quiet clicking slowly made it's way toward him. Koth, lost in thought, didn't even realize there was something there until it was about to strike. Turning around, he came face to face with an Oculus. Koth panicked and slammed his fist into the fiend's eye, and then strengthened his fist as he swung again, smashing the phyrexian's eye into pieces. The Oculus dropped like a rock, and Koth's thoughts rapidly processed questions and answers. If he planeswalked, there was no way a phyrexian could have gotten through, so did he leave Mirrodin, or was he still trapped? Fear started slowly gripping Koth, but the sound of laughter disturbed all of his thoughts. "Yes, strange man, let the fear devour your mind....I want to see all of your nightmares..."
Koth spun around, desperately trying to find the voice's owner. "Who goes there? What do you mean see my nightmares?!?" he shouted in reply.
"What I mean, little man, is that your mind's demons are about to try and rip you apart....and after I examine these nightmares of yours, I think I'll pay a visit to a few old enemies in Akros...I might even use these new nightmares to try and make that fool Phenax see who really owns the secrets of this plane...."
Koth's anger filled his chest. Whoever this was, they reminded him of Tezzeret, and the last time he and Tezzeret met, Koth was smashing constructs in a frenzy trying to keep the mad artificer away. He could tell that this individual had some bad intentions, just by the cold tone of it's voice. Whatever this threat was, it was obvious it wasn't letting Koth go. He might not understand the game this person was playing, but Koth knew one thing: the only way out of here was through whoever was pulling the strings from the shadows. And Koth fully intended on getting out.
Koth's deck may not have all the tricks that Ashiok brings to the table, but Koth has the aggressive power to crush Ashiok and the nightmares under a pile of stone. Since the cave feeds off of Koth's most recent memories and dreams, he'll have to dig deeper in his mind to bring out his whole arsenal of spells and bring some old friends back to punch through Ashiok's horrors. Your early game is to simply pound away at Ashiok's life with creatures like Plated Geopede and Raging Goblin. Around turn three, try to bring out a Rockslide Elemental. It's one of Koth's strongest creatures, gaining strength every time a creature falls, and can easily overcome all of Ashiok's defenders if he's left to grow. Ashiok will try and bring out early game defenders and a few of his artifacts to start causing you trouble, but cards like Smelt and Grotag Siege-Runner and made for these problems. Mid to late game is all about keeping your aggression on Ashiok. By then, your more powerful creatures will be out and charging at Ashiok's terrible creatures, so now is the time to start making sure they get through. Cards like Brute Force help keep your bigger Creatures alive while bringing down Ashiok's defenses one swing at a time. If things get too out of hand, just call upon koth himself to finish off Ashiok. Koth's abilities bring even more power to your attack, shifting Mountains into 4/4 beaters. And, if you keep Koth's geomancy going long enough, eventually he can give you an emblem that makes your mountains damage Ashiok and the horrors he plays! In the end, Koth's determination to survive and save Mirrodin will allow him to give Ashiok the rude awakening he deserves.