White to play and mate in 6
1.Ba5 (threat Bb6 mate) 1...N3xa5
2.Bxa5 (threat Bb6 mate) 2..Nbxa5
3.Bxa5 (threat Bb6 mate) 3...Nxa5
4.Bxa5 Nd7 (forced else 5.Bb6 is mate)
It does not matter which Knight takes which Bishop when it
comes to a5 the result is the same. Mate in 6.
The field of composition can be just as rewarding as playing a beautiful combination.
You can imagine all the fun we had adding Bishop after Bishop and Knight after Knight
to the problem.
OK it has few duel solutions which is not the done thing.
But it's sound, and more to the point. It's entertaining.