To claim the title of being a Ninja is not an easy one. In popular culture, Ninja have assumed an almost invincible status, using nothing more than reflexes to evade attacks and precision attacks that can quickly bring down even the mightiest foes. DnD has this element called "balance" that prevents you from rolling up an all powerful Ninja. The build I detail below is a poor approximation to whatever you may have conceived a Ninja to be (in no small part because everyone conceives Ninja to be something a bit different).