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Madara mentions that on this page in Chapter 560.
Going back to the previous page, it seems the sight of an allied army causes him to say this. He then states this person seems to have a plan but it doesn't seem to be going well due to him (Madara) being revived "into this kind of state" (the war?).
Alternatively, he could mean the IWR technique that was used rather then the technique he had hoped Nagato would have used. I'm leaning more to this one because, soon after, Kabuto assures him his IWR is a special version and he is completed beyond what he was in his prime.
The puzzling piece is the 'HE'. Is he referring to to Tobi or someone he knew that could use IWR? - Orochimaru or the 2nd Hokage.
That aside, another interesting thing to note this time in Chapter 561:
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Madara glances under his armor and states that Kabuto has "certainly prepared well" after he realizes what's going on. Immediately after he asks if Kabuto knows of "OUR plan" to which Kabuto knows nothing of in detail but assures Madara he is on HIS side (Madara). He then confirms that Tobi is NOT Madara Uchiha in any shape, form or fashion.
I believe Kabuto has used the one Zetsu given to him by Tobi to constantly supply Edo Madara with Hashirama's power thus making his Edo "special" compared to the others. However, the plan that they speak of and exactly who they are referring to had baffled me completely and any back-tracking through time just doesn't add up right.
Oh Kishi, you troll you.
Discuss.