Actually, now that I look at it. Madara's "will" reminds me a lot of Orochimaru's Cursed Seals. It turns your skin colors and it apparently contains the other's influence. I wonder if they're related.
Well Yamato obviously just sucks with it. There's always been something weird about Yamato's Wood Style. Everything he makes is, like, precut. Like cut timbers and structures. While everything Hashirama, Madara and Obito makes looks like natural tree growth. I'm not sure if the difference is meant to be significant or not.
Seeing how Madara used it against the Kages is probably a much more accurate representation of the Style's true power. And apparently Hashirama could use it to regenerate Wolverine-style.
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347:
Everything bad that ever happens is Danzou's fault.