A decisive queen transfer with two concrete ideas: 2 R(Q)h3 with mating motifs, and 2 Qg2, creating deadly threats at g7 and g8.
After 2...Qg2 , due to the double threat of 3.Rg8+ and 3.Rh3! Qxh3 4.Qg7# Black resigned.
After 2...cxd5 3.Qd4 mate is inevitable, so Black has to give up a piece.