Board Thread:General Discussion/@comment-4976518-20140808063123/@comment-27565137-20160310005900

DarkMuse616 wrote: In the end it might be more valuable to ask how any sensory type might change when in bankai and try to apply that to Aizen, that's why my previous post suggested that it would create a delusion about the world rather than just create illusions as I doubt another sensory type like Sakanade would grow to making his sensory alteration into a real change in the world. I also think it needs to be explained why he never went bankai, as every other captain so far has had a good reason for not using it which makes me think powerful sensory type zanpakuto like Kyoka Suigetsu and Sakanade probably have some huge disadvantage that makes bankai inconvenient to use flippantly. It's also possible that Aizen may have fused with his zanpakuto and can use its powers himself which would explain how he was able to confuse Yhwach's sense of time

Yes that would make sense. If some remnants of his zanpakutou powers were left inside him, when it disintegrated.

And also, the hypothesis that Aizen bankai has some huge drawback might explain why we never seen him use it. Gin explained that only the one holding Kyoka Suigetsu was the only one immune to its effects. But maybe the bankai removes that protection. Maybe Kyoka Suigetsu in its bankai form creates this well... Lets call it a genjutsu type reality within a certain radius, and everyone inside it would be affected by it, even Aizen. And seeing how much of a control freak he was. One has himself would never allow himself to be left vulnerable to his bankai whims.