You are the Enemy

This is from the Nik episode where Raph's mind becomes controlled by the Shredder, and Raph is pitted against Leo in combat on Shredder's behest.  Leonardo insults Raphael and gets that world famous temper going, and that's what causes Raph to expel the brain worm that was keeping him under Shredder's control.  Truly, that is one of the best TMNT episodes ever.  If Leo hadn't taken the direction he did, Raph may have finished him one on one (as he almost finished Shredder before the Shredder ordered Raph to stop just before taking him down). 

Great art!