Duel of the Gemini

Void

A world with no walls, no barriers, and no horizon stretched out under the inescapable darkness of the Void Realms. In a space untouched by time or nature, the Dragon-Planeswalker Nicol Bolas had carved the perfect fortress, and the perfect prison. A lone expanse of land artificially crafted from mana drifted endlessly through the Void, carrying with it the essentials for life: atmosphere, gravity, light. It was at once completely isolated – unreachable except by the most powerful magic – and connected to every plane and every part of the universe. It was this connection that Bolas would use to eradicate the manas of White and Green forever.
A portal opened beneath a fierce, rain-less storm. The entrance to the artificial world had taken many days for form, and would not last long. It had to be capable of transporting its user into the Void Realms, without allowing their body or consciousness to be absorbed and sent onwards to a distant plane. Instead, it acted as a tear in the Void, a rift that the spaceless dark struggled to close with every passing moment. As Eldranis stepped through he felt the surging mana of the portal resisting the pressure of the Void. Incredible surges in mana of the three colours Black, Blue and Red fought for supremacy on the balance-stricken plane.
Free of its traveller, the portal collapsed shut. In the distance in front of him, Eldranis could see three figures, all of whom he recognised immediately. The Original of Blue, Jace Balaren, and the hybrid Tezzeret were busily working on an elaborate device surrounded by glowing machinery – enchantments designed to protected it from the destructive influence of the Void. Behind them, Liliana Vess was on her knees, held tight by a powerful binding. All three were facing him with mixed expressions of confusion and alarm. Tezzeret was the first to approach.
“You! What are you doing here?” his twisted face broke into a sadistic grin. “Have you come back here to die?”
Beneath his shroud, Eldranis smiled to himself. “If you think you can kill me, then by all means, try.”
Tezzeret let out a shocked laugh, and looked over his shoulder at Jace. The Blue mage was quickly losing interest in the matter, as was so often the case, and waved his hand to indicate Tezzeret could do as he pleased. His grin widened diabolically as he pulled back his etherium arm. Mana collected in his palm, drawing directly from the artificial world around them. In a matter of moments it had built to a devastatingly powerful charge and with a mad scream he hurled the concentration of magic towards his opponent.
Eldranis’ face betrayed no emotion as he lifted his good arm to meet the volley. If unchallenged, it was a deadly shot, but it was no serious attack. Holding his arm out straight, he summoned the barrier he needed to block it. A wall of White mana appeared instantly and the  attack crashed against it adding to the noise of the lighting strikes overhead.
Tezzeret laughed aloud and crouched liked a sprinter about to run. Launching forward he hurled himself into an improvised vanish, a fast but imperfect option. Eldranis watched the path of the teleport through the air and traced the spot where Tezzeret would appear above his left shoulder. The Planeswalker cackled as he raised his palm for a direct attack.
Eldranis’ left arm flew out from under his cloak and caught the strike in midair. For a moment the two mages stood suspended in place as mana surged between them. It was Eldranis who finally conjured enough force to push his opponent back, and watched as Tezzeret landed easily on his feet, still laughing. This was a man who had spent lifetimes obtaining the power to defeat any enemy. It had been too long since he’d had a real challenge, and he was determined to enjoy this fight to the last. Flexing the muscles in his neck, he brought his two hands in front of his chest and began charging for a more powerful assault. It was then that they heard Jace calling.
“Tezzeret! It’s the other one! They’re both here!”
Confused, Tezzeret followed the direction of the shout with his eyes, not allowing his hands to fall or the charged mana to dissipate. Sure enough, past where Balaren was standing next to the device, where Liliana was being held, there stood Eldranis, his damaged arm visible at his side. Tezzeret’s mocking grin became twisted with anger as returned to face his original opponent.
“Who are you?!” he cursed. A slow hand deliberately pulled at the shroud to reveal a triumphant smile unmarked by scars.
“This ends now,” declared Sorin.
Tezzeret roared angrily and burst forward, still holding the charged mana between his hands. From inside his cloak Sorin pulled out the golden blade from Rakdos’ cavern. Charged mana ran through the blade like a conduit as he met Tezzeret’s attack in the air. With a devastating clash the two attacks exploded sending both men flying. Meanwhile, Balaren was on his feet and moving towards the real Eldranis.
Sorin knew he was out of time. As they were, the Blue mages were as likely to kill Liliana as allow her to escape. Dropping the sword he vanished in a cloud of black smoke, narrowly avoiding Tezzeret’s mana-charged fist. He reappeared on the other side of the device, positioning himself between Eldranis and Liliana on one side, and Jace and Tezzeret on the other. Balaren seemed to be part way through an incantation.
“That’s far enough,” Sorin announced. His right hand pulled his cloak away to reveal something hanging from his belt. Everyone recognised it immediately as one of the Lyzolda’s capsules, containing the concentrated fire of Chandra Nalaar. The Blood-Witch hadn’t been particularly pleased to see him again so soon, and had outright declined to give him a second capsule. It was only after learning of his transformation in the temple that she finally accepted, bitter in the knowledge that refusal would have meant an all-out war with the Orzhov guild. Whether he actually had the ability to carry through with that threat would be a concern for another day, he decided.
The Blue mages were silent now and stood unmoving, watching, and waiting. Eldranis was already busy at work trying to counter the enchantment that held Liliana at in place. Sorin stood guard, keeping her captors at bay. The anger on their faces was clear, but something else hid behind it. Fear, he realised, but not of him. After a few moments the mysterious fear overpowered their concern for the canister he carried. Without so much as a glance at one another the two Planeswalkers launched a simultaneous attack, a continuous bolt of pure Blue mana focusing on Sorin. There was nothing he could do but raise his arms to catch the twin attacks: he had to buy Eldranis more time.
The two mana streams continued to pour from the attacking Planeswalkers. Sorin could feel the pressure building behind his barrier and knew he would not be able to hold them for long. Neither Jace nor Tezzeret showed any signs of weakening, and he doubted either would fail before he did. In the end, he knew what he had to do.
“Eldranis! Do it now!” he yelled. The ground trembled at his command, staggering his attackers. He had only bought seconds before they would start their attack again. Without hesitating he pulled out the canister from his belt threw it as far as he could in the direction of the device. All three men dived to clear the path of the falling weapon, which landed beside the giant portal, smashing the small skull seal with a sickening crunch. 
It was as though a volcano had erupted right at the heart of the wasteland. The tremendous explosion tore out from the centre, obliterating the portal and continuing in every direction. When the smoke cleared, only charred earth remained, on which rested the unconscious bodies of the two Blue mages, alive by the grace of their illusion magics, and the three Black mages, protected by two extremely powerful White mana barriers.
From behind his barrier, Sorin could see Liliana, safe behind the wall which Eldranis held in place and free of Jace’s binding. He let the shield fall and felt the hot wave of dust and embers rush by him. As he approached, Liliana turned to face him with wide, disbelieving eyes.
“You!” She was on her feet now. “I was screaming at you! All of you! But you didn’t hear me! Instead you threw that, that thing at me!” Sorin winced at her words, remembering the orb-device Balaren had given him. She didn’t wait for him to speak. “They told me what they were going to do, what my magic would help them do. I…” the words caught in her chest. Sorin stood in front of her, waiting for her eyes to find his. After a long time, she spoke again. “I didn’t think you’d come for me,” she said.
“You don’t know me,” Sorin replied. He lifted up his damaged arm, and motioned for Eldranis to copy the movement, which he did resignedly. Despite the dust, Eldranis had removed his shroud. Liliana let out a shocked gasp.
“I knew…! That first time…! Something in your mana, and your eyes! But how… how is this possible?” She was glancing wildly between to two of them, but Eldranis said nothing. Sorin thought back to his arrival on Zendikar, to her knife pointing at his throat, and the path he had eventually taken to discovering the truth about Eldranis and their shared destiny. Finally, he took her head in his hands and tried to find the words.
“It’s hard to explain,” he said. “Eldranis and I… we’re the same. At least, we are now. He helped me discover what I was supposed to become.”
“The White-Black Planeswalker…” Liliana said slowly.
Sorin smiled. “The first of its kind, born in the Orzhov Temple no less.”
Liliana made an ironic face. “They’ll love that,” she said, laughing a little.
“Sorin, Vess, we’ve got a problem.” The Planeswalkers looked in the direction of Eldranis’ concern. He wasn’t facing them, but was staring out at the endless darkness that served as the sky for the artificial plane. Giant waves of mana had appeared and were crashing through the empty space, a violent mixture of Red, Blue and Black, swirling and colliding, gaining speed. Each impact of the crashing mana waves was like an explosion of thunder. After a few moments a path developed, forming the vague shape of an enormous portal in the vacant sky.
Something big was coming.