Rasenblade by Kakashi himself, he does a mixture of chidori & rasengan to make rasenblade but kakashi cant control it because its too powerful
I like Shikimaru's Shadow Technique! It's Awesome because he's a brillant character even though he doesnt want to be...
If it already has to exist: Fuuton: Rasenshuriken If it doesn't has to exist: Step 1: Kage Bushin no Jutsu (a few thousand clones) Step 2: Fuuton: Rasengan Step 3: Pwning time!