?? Takes the queen out of the line of fire. Nxc3 followed by Qxb4 was imminent, but this leaves the bishop unprotected after an exchange of knights. Maybe Qe2 or Be2 instead. Rf1 with a threat on Qxf7 checkmate would be tempting, though not sufficient.

Opens the diagonal to the white king and wins a a piece.

brings the white queenside rook to play at the expense of the pawn position. Retreating the white light bishop was an option too.

? This makes the black's advantage in material more pronounced, and the black dark bishop is not an imminent threat.

chases the queen to make room for the kingside rook

! sets a trap and limits the mobility of the white queen.

? Qh4 would have disallowed opening the g-file for the rook.

Kg1?? Bf3+ would capture the queen for free.

Prepares or the final assault on the white king. The c-file pawns can't last.

Last line of defense.