
Far from being Brought Down to Normal as Ichigo and Urahara had assumed following his defeat, Aizen was rendered immortal and almost two years in Muken leave him more powerful than ever. His fourth and final evolution transfroms him into a Lovecraftian abomination that can fire energy bombs and generate energy circles to trap his target. His third evoloution transforms him into a Transcendent Being with Villain Teleportation, increased regenerative abilities, and superhuman strength. His second evolution gives him stronger durability and spiritual power. His first evolution increase all of his physical capabilities to an immense level, as well as advancing his already extraordinarily high spiritual power. Even if you do actually hit him, the Hogyoku gave him regenerative abilities that react when he is hit, as well as defense and strength augmentation. He had several Deflector Shields set up to protect his blind spots beforehand. Starting off, his Zanpakuto's Shikai ability makes him a Master of Illusion. Antagonist Abilities: Let's count them all. By his next appearance, he has grown so powerful he breaks several of the seals anyway, horrifying Shunsui Kyōraku. And I Must Scream: Aizen is ultimately sentenced to 20,000 years in Muken the deepest layer of Soul Society's underground prison, and his geven bindings that remove his senses. In order to satisfy his hunger for power, Aizen is willing to commit truly heinous crimes for the sake of his own selfish desire to achieve transcendence. Ambition Is Evil: Aizen desires unlimited power, but even Soul Reapers have limits and boundaries that they can't exceed. After-Action Villain Analysis: Not only is he subject to one at the end of the Arrancar Arc by Ichigo, he also monologues about Yhwach's endgoal in the very last chapter. When he grows bored of playing around, he decides to get serious on trying to kill them. Even then, it's only because Aizen is playing cat-and-mouse with them as he waits for Ichigo to catch up. It's all Tatsuki, Keigo, Mizuiro, Don Kanonji and Chizuru can do to stay away from him. Ordinary people die simply from being too close to him. Advancing Boss of Doom: In Karakura Town, Aizen strolls through the streets without rush. He evolves five times before he is finally brought down to a weakened state by Ichigo, which enables the Hogyoku to look past Aizen's hunger for power and see what he truly desires. Everytime he reaches his limits, or is brought close to death, he evolves in power level and appearance. This is thanks to the Hogyoku, which he implanted in his chest. Adaptive Ability: During the Fake Karakura Town battle, Aizen frustrates his opponents by constantly gaining new counter-abilities every time they think they've finally got him. He faked his death this way, distracted Komamura on Sougyoku Hill by making it seem he was somewhere he wasn't and made Hitsugaya stab Hinamori, thinking he was stabbing Aizen. Actually a Doombot: Aizen's Shikai gives him illusory powers, which he can use to convince people they're seeing someone they're not.
Also, anyone that touches the blade before the Shikai is released gains immunity as well.
It's also possible to sense his Reiatsu through the illusions he creates but only Yamamoto was shown doing that so it's unclear how practical that method is.
Achilles' Heel: His power cannot be used on the blind, meaning Tosen is immune to it, making him decide to recruit him as his lieutenant as a result. Despite this, he later gets very angry with Urahara for never having agreed with his point-of-view, because he can't understand why someone of Urahara's intellect would disagree with the way he sees the world. As a result, he even rejects the concept of truth and lies because that's just perspective, too. He claims that he is above all of this and therefore, can make his own rules as he goes. Above Good and Evil: Aizen reveals that people define their boundaries, morality and what's right or wrong based on their own limited understanding of the world.