Qb7 fork then chomp a few pawns try to promote and fork king and rook
@GrandLapin This is what I would play. Qb7 to start, forcing Rc1 to defend the knight. There now follows the decoy tactic Qb8+! Kg7, and then Qb2+ wins either the rook or the knight if the rook blocks.
Qb7 is indeed obvious however the best move is actually f5!. The deep reason for this being that if white pursues the knight right away, black shuttles the rook to f5 and there's no way to break through, the king is stuck in the first four ranks. Not the case after exf5.
i tested with engine after i guessed qb7 and ummmmm
EDIT: its at depth 63/99 and still saying qb7
@jdwhite42 Stockfish does weird stuff sometimes. It is confused by the position. I think
@grandLapin is correct. After the later Rf5 it's impossible to make progress.
@ChessMathNerd you're right. after f5, stockfish still gives +2.6
I would use my brain and say Qb7 as it is an excellent move (for me)
@GrandLapin