Hey guys, Here is my gist on why kage bushin is a big deal (and possibly a forbidden jitsu) and the whole deal with the chakra requirement.

Since this technique divides your chakra its not THIS TECHNIQUE that would kill you but the next one. (which if you are fighting their will PROB BE a 'next one'

Take Kakashi for example, he could only do 4 chidori's a day... now this means if he made like 4 shadow clones then tried to do a chidori, he would prob use up ALL his chakra and possibly die.

If he made one shadow clone, got it destroyed and made a second one... the same result would happen.

And these numbers come from a fresh start not mid battle.

In short, ppl liek Kakashi cannot use many of Naruto's kagebushin strategies at all in a serious battle or risk dividing their chakra up far to much to make the next move.

Now I know that the wind rasengan of naruto's took allot out of even him (it said that he at first could only get one a day, then he pushed it to 3 ) so with some one like Kakashi could never pull this off with a shadow clone's help as that alone just divided his chakra in half... again assuming he does this right from the start.

Also you can understand why they don't like to teach the kage bushin technique to just any one... Some one w/o MUCH experience in battle and their own chakra levels would EASILY kill themselves by going overboard. Naruto again is just the exception.

~David