Book Rule 2: "What happens if it is black to move?" Answer (here): "It is mate against all defences except 1....Rd5" So find a key that takes care of that particulate defence! Not easy? Well some of the mates may need to be changed (mutated).
This kept on looking to me like White was travelling down, and Black going up. After finally getting beyond THAT, figuring out the first mating move, I actually got tripped up a little on finding the mate in 1... kept using the queen.
Answer (here): "It is mate against all defences except 1....Rd5"
So find a key that takes care of that particulate defence!
Not easy? Well some of the mates may need to be changed (mutated).