how did madara kill time while in a cave?

[Flawž]

made zetsu turn into Kid sasuke and Did things to him.

 

[RikudoKami]

He was devising his plan & waiting for his Rinnegan to activate.

 

[Your Creepy Stalker]

Well, almost everyone has beat me to it, but

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[Jurian Uchiha]

Wrote the whole Batman series.

 

[Lightbringer]

mortal kombat with zetsu....the strongest became the main zetsu

 

[Madara ibn Lahad]

He probably found the magic con shell,asked what to do and it replied,''nothing.''.
So he sat there until Obito came along.

 

[SashaUchiha]

he slept... :|

 

[FatalChakra]

He was plotting he's ressurection and was maybe the mastermind behind a lot of different wars!

 

[Silverblade]

Pull some strings. Actually good question OP.

 

[johnny335704]

He enjoyed with the 2 androids he created by using gedo mezou.