wwall: Or 16...Rg8.
Perhaps best is 17...Rg8 18.Qxd3 Rg5.
If 18...Qb4, then 19.a3. If the Queen moves away from the a3-f8 diagonal, then 20.Qxe7 mate.
If 19...e6, then 20.Nd5 Qh4 21.Nc7+ and 22.Nxa8.
If 20...Bxd7, then 21.Nd5 Qh4 22.Nc7+ wins. If 20...Kf8, then 21.Qxa7 Rd8 (21...Rxa7?? 22.d8=Q mate) 22.Qa5 wins. If 20...Kd8, then 21.Nb6 axb6 (21...Rb8 22.Qf4) 22.Qxb6+ Kxd7 23.Qxb7+ Kd6 24.Rxd3+ wins.
If 21...Kc8, then 22.Nb5 b6 23.Qf3 Kb8 24.Qc6 Rc8 25.Rd8, threatening 26.Qc7 mate. If 21...Ke8 22.Nb5 Kf8 (22...Rc8 23.Nc7+ Kf8 24.Qd8+ Rxd8 25.Rxd8 mate) 23.Qd8+ Rxd8 24.Rxd8 mate.
Perhaps Black can survive 22...Kc6. If 22...Kb8?, then 23.Rxe6 Qxe6 24.Qg3+ Bxe5 25.Nxe5 wins.
Or 23.Ncd6+ exd6 (23...Kb8 24.Qc2, threatening 25.Qc7 mate) 24.Qxd6, threatening 25.Qc7 mate.
If 24...Qxb2 25.Rc7, threatening 26.Rxb7+ Kc8 27.Rc7+ Kb8 28.Nc6 mate.
Or 25.Qf3 bxa5 26.Nc7, threatening 27.Na6 mate.
After 26.Qf3, White threatens 27.Qxa8 mate.