Barragan didn't waste any time unleashing his rotting mist. Khan raised his shield in order to make a show of blocking it. Khan was not worried, thanks to the perk Time Keeper. However, something happened that neither of them expected. Instead of surging past the shield or building up around Khan, it just seemed to be absorbed by the shield.
When the attack stopped, Barragan was shocked by what he was seeing. The spikes on the shield weren't spikes but teeth, and they had opened. The teeth were now on the edge of the shield, and making up the center was an abysmal void. The shield closed shut
and the aura of the rotting mist was permeating from Khan's sword.
Barragan was enraged by the notion that Khan just stole his power. Khan, not wasting a second, rushed Barragan. Barragan brought down his ax in an effort to blunt Khan's momentum. Khan attempted to parry, but the moment the blades met, Khan's sword started cutting through the ax and Barragan like they were both made of butter. Barragan was surprised that Khan's sword was controlling his rotting mist so easily. Barragan tried to yell out a curse, but only garbled noise escaped from his mouth as he dissolved into nothing.
Khan stood there for a moment, going over what just happened. Khan could tell that his shield allowed him to consume the attacks of others and release them through his sword, but it was not infinite. It would eventually run out, Khan could choose when and where to use it, and if he focused, Khan could sense that he had used a fourth of Barragan's mist. Khan smiled beneath his helmet, thinking, 'This is a pleasant surprise, but with Barragan dead, I probably won't be able to restore it anytime soon, oh well.'
Khan left for his next engagement as the battle continued to rage. Both the Soul Reapers and Aizen's Arrancars felt an uneasiness as the energy from both comrades and foes began to disappear.
...
Apacci, Mila Rose, and Sung-Sun stood there. They located their targets, but they were in three separate locations, and they weren't alone. While Apacci and Sung-Sun argued about the best way to achieve their goals, Mila Rose asked, "Do you think Master was serious?" Apacci and Sung-Sun stop arguing for a moment to think, then Apacci said, "I think Master is ambitious and whether he was telling the truth about what's to come or not, it doesn't matter we swore ourselves to him and we'll follow him where ever that leads." Sung-Sun added, "Master has achieved everything else he claimed, I mean, he turned us into Prefect Arrancars, like Lady Harribel. If he says that we'll have whole other worlds to conquer after the Soul Society falls, I believe him." Then Mila Rose said, "Agreed, but that may be moot if we don't get these people from the Visords." Apacci and Sung-Sun nodded, then Apacci said, "Our targets are Mashiro Kuna, Lisa Yadomaru, and Hiyori Sarugaki." Then Sung-Sun added, "Our current issue is that none of them are together, nor are they alone. If we take them one at a time, the other two might get tipped off, and if we split up, we might get overwhelmed.... no matter our choice, we could use some extra hands."
The Tres Bestias quickly noticed Nelliel, Pesche, and Dondochakka approaching. When they arrived, Apacci asked, "What are you three doing here?" She was somewhat skeptical that these three showed up right when they needed some extra hands. Nelliel said, "We got an early jump on our targets, so Harribel wanted us to assist you in acquiring your targets." The Tres Bestias looked at each other, then Mila Rose said, "Well, having the extra hands can't hurt." She then told them the situation.
They agreed to split up. Sung-Sun and Pesche went after Hiyori, Mila Rose, and Dondochakka went after Lisa, and Apacci and Nelliel went after Mashiro.
....
Soi-fun was not having a good day. First, her request to be a part of the advance team was denied, and because they were too slow, Lady Yoruichi was now hunting her. Soi-fun had been caught off guard, and her lieutenant was knocked out in an instant.
She knew Lady Yoruichi was toying with her. Every missed strike, every taunt, and every close encounter told Soi-fun that Lady Yoruichi was leading her to somewhere specific.
Soi-fun wanted to fight, but Yoruichi kept whispering in her ear. Yoruichi's actions caused Soi-fun to think that this was a ploy to get the Hollow known as Khan to lower his guard. Soi-fun found herself at a dead end, suddenly without knowing why she found herself quickly losing consciousness. The last thing she heard was Lady Yoruichi whispering, "Sleep now, and don't worry, we'll both be together as sisters serving the master."
.....
Aizen was unsure about the situation. The battle was progressing more or less as he expected, but instead of making a big splashy entrance, signaling his betrayal. Khan had come in quietly, with his followers hidden, but their actions were still being felt.
This situation was not unfavorable for Aizen, but his inability to track Khan or his followers was unfortunate. Aizen wanted to play around more, but the situation dictated that he deal with Yamamoto and head to the Soul Society.
After a bit of searching, he located Yamamoto in a fight with Wonderweiss. He had intended to let that fight drag out, but he decided to force Wonderweiss' transformation. Looking like a real monster, Yamamoto didn't hold back and killed Wonderweiss. Aizen appeared to reveal Wonderweiss' trick as all of Yamamoto's fire that Wonderweiss had consumed was released in a massive explosion.
Yamamoto stood there in the center of the crater with burns on his body. Aizen proceeded to stab him, Yamamoto grabbed Aizen's sword, declaring that Aizen was not an illusion. Aizen used his free hand to strike Yamamoto and knock him to the edge of the crater. As Yamamoto lay there struggling to remain conscious, Aizen, now at the center of the crater, raised his hand, ready to finish Yamamoto off, mostly for revealing his zanpakuto's flaw. Then suddenly he found himself unable to move, approaching from his left came Khan. With one quick motion, Khan cut off Aizen's head.
...
Khan was silently watching things unfold. He watched as the Dark Ones were torn to pieces by the Privaron Espada. He watched as Yoruichi toyed with Soi-fun, and he watched as Rukia guilted both Momo and Rangiku into surrendering.
Khan was amused by how the Tres Bestias and the Nelliel troop easily and rather comically collected from the Visords. The fight was progressing faster than Khan had anticipated or perhaps the manga and anime made it seem it should've taken longer. The massive explosion signaled to Khan that the fight between Yamamoto and Aizen was close to ending.
Khan arrived in time to see Aizen knock Yamamoto back. Khan saw that Aizen was getting ready to finish Yamamoto off, and while he was tempted to let Aizen do it, Khan had a different end in mind for Yamamoto. Khan charged in, he used Shadow Manipulation to immobilize Aizen. Then with a quick strike, he cut off Aizen's head. With his back to Aizen's decapitated body, he got ready to use Barragan's mist.
Suddenly Aizen's sword pierced the left side of Khan's chest. Khan's armor shattered, while not unexpected it still hurt. Then Khan heard Aizen's voice Aizen's head went no more than a yard before it rushed to reattach itself.
As Khan dropped to his knees Aizen say, "So your power lies in manipulating shadows. That answers so many questions I had, and I must say it is quite the experience to have my head cut off. Now here is my conundrum that sword will kill you if I leave it in there for seven minutes, but that leaves me a little more vulnerable than I like. If I remove it, that injury while fatal, there is still the chance you might survive, but lucky for me there is an easy way to solve this problem."
Aizen said all that while standing behind Khan. Aizen raised his hand and with one strike he sent Khan's head flying. As Khan's head flew Aizen said, "It really is quite the experience, I hope you can enjoy it as I did, if not... well I can live with that."
As Khan's head went flying out of the crater he had a single thought before it hit the ground, 'Well... shit.'
As Aizen retrieved his sword Gin appeared next to him and said, "You had me worried there for a moment when your head started to fly off like that." Aizen gave a small laugh and said, "Yes, lucky for me the Hogyoku is now integrated with me. Let's head to the Soul Society, there is no one left to stop us."
A gate opened up and Aizen and Gin entered.
Yamamoto has fallen completely unconscious, and Ichigo's father is currently trying to convince his son that they must go after Aizen. Completely unseen was Khan's head slowly rolling back to his body. After the ripped flesh heals, Khan regained consciousness. After quickly checking to see that he was really back. Khan asked the system, "How am I alive? I thought I received two fatal injuries."
[Notice you only received one fatal injury, your body has a quirk similar to dextrocardia. Your insides are in fact mirrored so nothing vital was hit.]
Khan sighed and got up. Despite that little scare, everything had more or less as planned. Khan said to himself, "I can still beat Aizen and Ichigo to the real Karakura Town." As he entered the Shadow Nexus Khan thought, 'I'm definitely going to enjoy what happens next.'