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This puzzle is a tough one. It is - if you don't see the idea or continuing line. But once you see it, you'll understand it.
This just occurred less than 10 min ago in a blitz game I played online.
I am Black. White is in absolute dire straits but Black must play carefully.
White had his King run up the board to h4 to escape the pin of his Knight on f3.
I did not see the following line unfortunately and missed the opportunity to end this in the most efficient manner.
Black to play and mate (Hint: in less than 5).
Answer can be found by highlighting the brackets
[
1... Ng6+
2. Kh5 Qg4 and White cannot stop Nf4# or Qh4#2. Kh3 Bd6! and White cannot stop Qh2# or Qg3#]