ninjestic
Derived from the words ninja and majestic, "ninjestic" is an adjective used to describe someone with great skill. If you wish to describe an action, you should use the adverb form: ninjestically.
If a friend leaps up a giant rock, you might tell them that they are a ninjestic climber. If the paper a friend wrote in study hall before class receives an A, you might tell them that it was ninjestically written.