"Oh... now..." The Doctor spluttered, ever-so-slowly approaching Missy, both hands raised. "You wouldn't want to do that."
"Oh, I think I would. It's set up to no longer send those it disintegrates to the Nethersphere." Missy purred. "Say something nice." She moved her disintegrating device over to the Doctor, then shook her head and clicked her tongue in a piteous way, and aimed it back toward Clara who flinched at the sudden change of decision, and Sebastian's eyes widened like a deer in the headlights. Remembering what'd happened to Dr Chang even though he'd obeyed her order to say something nice, Clara decided to keep her mouth shut. Not wanting to die was a good enough reason to.
"What?" The Doctor furrowed his brow in confusion. Then he understood. Of course. Missy wanted to dispose of Clara, and only Clara. "But why?"
"She's outlived her usefulness. Don't you remember, Doctor? I set her up to be with you, a long time ago. It was a test of your strength, and you have passed. You..." Missy giggled sadistically, adjusting her grip on the device. "It looks like you're strong enough to be my husband, if you can withstand the will of such a controlling girl. And of course, I can't have her continue to disrupt my plans."
The Doctor ignored her reference to The Master proposing to be his wife, looking back at Clara who had her hand over her mouth, then back to Missy.
Missy giggled. "Remember me, my clever boy?"
Clara gasped, stepping backward still with the hand over her mouth, hiding her shock. Sebastian gripped her shoulders, attempting to comfort her. A long time ago when she had a computer problem at home and couldn't connect to her Wi-Fi, she'd called technical support. A woman in a shop had given her The Doctor's number, allowing her to reach him when he was in the thirteenth century. Subsequently, he'd later come to her home and rescued her from being uploaded to a cloud of data. From then on, they'd bonded. Concern crossed The Doctor's features. Now he understood what Clara had meant about The Doctor changing ever since he'd regenerated. The incident with himself being a caretaker in her school, particularly when he'd seen Clara talking to a lookalike of his previous regeneration... now those feelings were being brought to light.
As The Doctor's mind raced with the implications of what Missy had just revealed, some Cybermen began to break off from their exit paths toward the exit of the building, and turned their attention onto The Doctor and Missy. Approaching the four and surrounding them, the group of Cybermen blocked off the two corridors that would've otherwise led to the exit and saluted. Missy looked at them as if trying to find a fault, then back at The Doctor.
"Don't tell me..." Her smile turned to a scowl. The Cybermen reached up to remove their helmet's front plates, steam hissing as they did so. And then The Doctor was left staring at those who'd he had left behind prior to arriving in this mausoleum. The Half-Face man from London. Gretchen the soldier from inside the Dalek. Matthew the policeman from Clara's school incident. And then numerous people from the Orient Express. Of course, he didn't recognize all of them or remember many of their names, but could he really burden himself with this additional knowledge? Thankfully, the robot sheriff from his adventures in Sherwood wasn't there - he'd had enough of the merry men's antics after five seconds - but that provided little comfort. Just what were they here for?
"From the ends of the Universe..." The Doctor muttered to himself. "Taken out of their graves and rightful place of death. Reassembled. Reused. Even Half-face wouldn't have stood for this."
"Everyone..." Clara gasped, taking her hand away from her mouth. She stepped ahead of Sebastian, toward Missy and the group of Cybermen surrounding them. "I'm so sorry..."
"Don't worry about it!" Gretchen the soldier saluted, with a proper soldier's salute. The Doctor rolled his eyes, as he recalled the fashion of that salute as someone trying to give themselves a concussion. Then turning her focus on Missy who still had her device aimed at Clara, she nudged a thumb. "What do you want us to do with her?"
"Lock her away!" Clara ordered, with a backward step. She pointed at Missy, giving the command again. The Doctor poised himself for a small struggle, but he couldn't have predicted what happened next. Scowling, and with a jerk of her arm, Missy pressed the button on her device to send a laser beam toward Clara. As the beam flew through the air, time seemed to slow down. An ironic act for a Time Lord, but it was not the Time Lords that were affected by time slowing to a crawl. Rather, it was the human stood behind Clara. At least, he was stood behind Clara until a second ago. In the time that it'd taken Clara to take a backward step and for Missy to fire her deadly laser, Sebastian had launched himself in front of Clara, taking the full brunt of the impact. His yell as he was disintegrated into a thousand pieces was eardrum-piercing, and Clara was thrown backward by the force of the explosion. All the other self-aware Cybermen jumped from the shock, and even Missy gasped. The Doctor looked at the pile of ash on the floor, and felt the same feeling he'd just experienced about twenty minutes ago. However, this time... it was personal.
Fury in his eyes, The Doctor reached into his jacket. Missy flinched as if he was reaching for a weapon of some sort, but remembered that his Sonic had been disabled. By her no less. The Doctor took out something small and metallic - too small for her to see properly - and tossed it over his shoulder toward Clara as he advanced toward Missy. Clara grabbed the small object with a gasp, and looked at the pile of ash on the floor that had once been Sebastian. Wiping a stray tear from her eye, she stood up and then ran in the direction of where The Doctor had left his Tardis. The crowd of self-aware Cybermen parted to allow her through. Concerned with The Doctor's sudden advancement despite her infatuation for him, Missy stepped backward, a hand finding the railing of the bottomless pit and gripping it. She looked at her disintegrating device. A small screen on the side of the device was partially lit up in green. Approximately ten percent. It inched to fullness slowly, overtaking the red that otherwise filled the small screen. It was recharging, but while it was recharging, she couldn't even use it to threaten The Doctor. And he knew that.
Suddenly, The Doctor launched himself forward, much to the shock of the cyber-spectators and Missy. She screamed as she was launched by his gravity over the railing, grabbing onto his red-trimmed jacket. And so The Doctor fell too, pulled over the edge with a Scottish yell. The Cybermen looked at each other and dashed toward the balcony where the two Time Lords were last seen before their untimely fall, leaning to look over the edge. But there was nothingness, other than the sight of multiple levels of the mausoleum. Their eyes darted to the Nethersphere that hung above.