23...Nxh3+

Black delivers one powerful blow after another. The Knight can't be taken with 24.gxh3, because 24...Qf2+ 25.Kh1 Qh2 is mate. The escape by 24.Kh1 loses to 24...Nf2+ 25.Kg1 Nd3 26.Qd1 Qf2+ 27.Kh1 (or 27.Kh2) 27...Re6.

Next move: 24.Kh2