I wonder if you can spot the move that is winning. In fact to spot the obvious threat is not that difficult, I in fact saw this threat. Just at the board it seemed that white has obvious defences against this threat, so this move should be prepared somehow. It turns out that black has resources against any and all white defences, in very elaborate ways. I think this requires master level vision, or may be I'm just pretending this to make my lack of vision less shameful, I don't know.
Black to move an win
Black to move an win