"Surprise." The Emperor croaked, handling the word and cracking it, splitting it as if to reveal the dark side of the very language.
Luke tensed all over, like a shiver ran through him, as Vader's adamant mask turned toward them. Spurred on by the image of the sphere, possibilities flooded and assailed Luke's Force-conscious mind; the madness of this universe could spread and the splintering Force fail to find it, and here in this challenge was the endgame. The first time's failure hung over his head like a dark cloud, but now Luke felt stronger and knew more, knew tens of ways to wound a man body and spirit without killing him, so maybe this time would be same/different with another chance...
The Emperor kept speaking, looking down at Luke with his yellow gaze unfocused. "It is I who have the control of all that has transpired. I allowed there insignificant rebels to take their positions, because this entire universe will be as nothing when there are no Jedi left to defend it!"
Quietly, Luke said, "Kit still lives."
The Emperor gave a jagged smile. "Master Fisto and I are old acquaintances. I am sure dealing with him will be no trouble."
Luke showed his teeth for a second, looked around, felt the Force and the past--what is the difference?--and pivoted.
Many things happened at once. Luke called the universe-machine to his right hand and his lightsaber to his left. The Emperor kept his grip on the machine with hands as pale and curled as Dagoban spiders and the lightsaber hilt fit perfectly against Luke's palm, and Darth Vader lunged from his place at the apex of the stairs with his red lightsaber growing into a horizontal preparation for attack. Heat beat against the rough walls and made the air thick, so that it was breathed in as well as pushed against black clothing from without.
The Emperor laughed, spreading into the Force arrogance and sour amusement.
Luke didn't bother with the failure of his telekinesis; it was part of the plan. He took the lightsaber in both hands and twirled it, then threatened the Emperor with the lime-green terminal curve. He noticed that he nearly matched the stooped ruler in height. The old man raised his free hand in a claw, tucking the machine against his shrouded side and hissing like a cornered animal with jagged yellow-gray teeth. Luke turned from him and met his father's lightsaber in a horizontal overhead block to a bone-shivering two-handed swing. Maybe something in Luke's eyes told of a sinking, falling utterly different than the negative depth of the dark side, and maybe it was a reflected shadow in the focused clear blue.
"Kill him." The Emperor said, lazily.
Luke back down the steps, watching, and once every moment or so they would trade strikes. Vader was silent, malevolent, a force unto himself. Attacks came slow and purposeful, and Luke blocked them easily with exaggerated twists, precisely crackling strikes, and the growing awareness of the will of the Force.
Both stepped onto the rock of the lower level at the same time, while Palpatine settled back into his throne. Quick as thought--slow as the human mind--Darth Vader gestured and tore molten rocks from the sluggish river of lava beside and behind Luke. They arced toward him and he did not bother to dodge but flowed with the Force, letting the molten drops these missiles trailed splash against him if that was their natural direction, because they only scored holes in his dark uniform and made tiny heat against his skin that he could surrender unto the Force as easily as he could keep his breath even and deep while heavy lightsaber blows continued to rain down. A flaming stone arched across Luke's left shoulder and fell to the floor to his right; another flipped across the floor toward his ankles. Luke moved with the Force and the fist-sized missile took another course toward Darth Vader. The Sith sent it back, and for a moment their hands almost met with the cooling stone suspended between them, skintone synthskin against black leather hiding golden circuitry, before Vader fisted his hand and the rock shattered, and more were flying at Luke from all sides along with streams and gouts of fire. He disengaged from the lightsaber fight in a violent sweep that deactivated his blade and flowed into a shoulder roll that took him nearly underneath the simple steps. Shadows fell over his face; molten fire pocked and colored the stairway neon as Darth Vader paced forward.