White mates in 18. You know this BNK vs. K endgame, but could you finish him off quickly? (Note: I've put in some comments. to check them, finish the puzzle and look back)

(Note: Other variations are in the move list.)

Nice puzzles. I couldn't remember much about how to checkmate with knight and bishop except that you have to give up a lot of tempos and make a certain pattern :D took a while. Thanks for sharing