Pre-Suit Vader Vs. Exar Kun/DN Luke/Naga Sadow (with a twist...)
Pre-Suit Vader, except he is oddly different, the momment before he would have jumped across the molten lava at Obi on Mustafar he was ripped out of reality and time to a unknown plane by the force itself. There he was trained for one thousand years to master his powers, saber combat, hand to hand combat, to refine his knowledge and understanding of all and everything, to fully understand the force, to the point of being able to control the very essence of the force itself, to melding with it, able to manifest himself on any plane he choses. He was also taught knowledge and understanding of all that is, of all that came before him and after him. Although aged one thousand years his physicality is of him at his prime, no longer affected by time he is beyond aging.
Shortly one day before the time arrival of Anakin in the outter plane where the battle will take place. Exar Kun is brought upon it. There, in a brief amount of time, he slaughters the Masters who would have been the observers of the battle, in attempt to return to his own reality, though only to fail.. A day later, Anakin is placed within the plane, and Exar Kun wittnesses the portal open, Being a sith lord that he is, his reaction is attack now, ask later.
Before they could clash sabers together, both are then teleported to the battle arena, where DN Luke, and naga Sadow are already in battle.. Now the true war begins...