Ok, from what we've seen so far, Ninja's have some pretty interesting powers, most of which could be wide open to abuse.
We'll have to assume we're evil here (for some, that won't be so hard... heh...) what powers would you use the most, and take FULL advantage of, in the most deplorable and purely EVIL ways? (We'll assume you are free from the wrath of more morally assertive Ninjas.)
Personally, I can see myself tkaing full advantage of Kagebunshin and Henge (that transforming one); the possibilities to screw around with people are endless!