[FEN "r2qk2r/1bpn1pp1/p3pn1p/1p6/1b1PP2B/1BN2N2/PP3PPP/R2QR1K1 b kq"]

12... g5 13. Bg3


w b wb bw | w b wb bw

b     an
    


12...g5      an
    


13. Bg3      an