Originally posted by heinzkatHere was what my longest original solution would have looked like
I have mate in six for Black... several possibilities too along the way.
1. ... Nc5+ 2. Ka2 Rxa4+ 3. Kb1 Bc4 4. Ne3+ Kd2 5. Nxc4+ Rxc4 6. Ka2 Ra4+ 7. Kb1 Ra1#
But as SwissGambit pointed out you can win in 6 by playing 3. ... Kd2!! Sorry for the bum problem.