I'm not sure black's moves are best, which would make this puzzle a terrible one if it's true. Very cool to see the tide turn so quick, though. I never would have guessed just glancing at the position.
8. Nxc3?!?!
12...Qf6 is a bad move. 13. Qc1, either move the black queen makes will lead to checkmate the next move.
EDIT: I see you can do that too with mate.