How did Yamamoto's Bankai work in Bleach

Did Yamamoto Genryuusai use all his might against Aizen?

He didn't use the bankai because he couldn't use it.

His Bankai Zanka no Tachi absorbs the flames of his Ryujin Jakka in the katana blade. During the battle in the fake city of Karakura, Wonderweiss absorbed his flames. Later, when the flames explode in Wonderweiss' body, Yamamoto has to shield him with his own body, which left his own body in ruins. It can be assumed that either he was unable to activate his bankai or that the bankai would not be strong enough because he could not absorb enough flames.

If he had known Wonderweiss' abilities beforehand, he might have gone straight to his Bankai from the start.

Rikkin

Humm I get it, it really makes sense. I forgot Wonderweiss' ability, thank you!

Daz C.

Zanka no Tachi relies on flames no matter how you cut it. Wonderweiss should be able to accommodate them. The only ambiguity is how much Wonderweiss could handle, but there isn't enough evidence to tell if he would be overwhelmed.

Masked man

@DazC You miss my point of view. I didn't say he didn't use a Bankai because of Wonderweiss' abilities. He Shikai is very strong in itself, and like most Shinigami, he started out with it. It was being absorbed by Wonderweiss, and at this point there was no point using Bankai because the flames were gone. When the flames exploded, he had to use himself as a shield, which caused great damage to his body. So I said it was "reasonable" to assume that he would not be able to use his bankai in this situation. Either that, or you can shake it off and say "Kubo didn't think of it" and move on. Your call.

Daz C.

@Happy My point was what happened to Ryuujin Jakka's flames, using Bankai would give the same results for technical reasons. Regardless of its damage; Hence, it was a tactical move why Genryuusai stopped using his zanpakuto (long before he sacrificed himself) in order to quickly cope with his situation. The logic is there. The ambiguity I mentioned was to obscure the possibility of whether or not Wonderweiss could be overwhelmed by Genryuusai's power. Also, flames from Ryuujun Jakka are picked up in Bankai, but that doesn't make it necessary to reach Bankai (like it's okay to start with).

Ryan

It can also be suggested that his bankai would have had a devastating impact on the human world. He completely disabled Toshiro's powers, which were quite far away, by letting go of them because they even rendered the water in the air unusable for Toshiro. This may have held him back so that he never actually had to use it until he stopped the Wonderweiss explosion, and it was too late.