Board Thread:Rebirth: Story Time/@comment-4869113-20141109220441/@comment-24070327-20141110010755

Never under underestimate the potential for clever poisoning! Dimethylmercury (Number 7 on this LIST) could probably give us a dead Uchiha and Uzumaki with little to no detection. You could poison either of them at any point in time and they'd be none the wiser. Symptons wont show until months after the poisoning and by then it's too late. Let's not forget the fact that someone would have to be familiar with the substance to even realize that it's poisoning rather than some kind of disease. And even if they know it's poisoning and which poison it is, but that point it is far too late.

All of the raw, destructive power in the world wont save you from micro-problems that build up over time. Itachi, for all his raw power, was screwed over by a disease and even Madara freaking Uchiha succumbed to age. Even the Sage of Six Paths, who is far stronger than either Naruto or Sasuke, couldn't defeat the micro problems despite all of the immense power he wielded. So I doubt either Naruto or Sasuke could. You could probably just make a Water Clone that is infused with the poison. Deceive the target into destroying it and getting some of the water and substance splashed onto him. Poison effectively applied with target none the wiser. Target dies a few months down the road from an inexplicable illness for all anybody else knows.