Very subtle idea. black B at c5 is vulnerable.If 1.b4 it has nowhere to go.But black can exchange the other B first by 1…. Bxg2 2.Kxg2 Now by 2…. kb7+ he vaccates e7 for the B.Alternative 1.bxg7 Qxg7 clears e7 for the B. So, 1.Be4+ Now 1… Bxe4 2.Qxe4+ any 3.b4 traps the B.
1…. Kg8
2.b4 black has to lose a piece.
Very subtle idea. black B at c5 is vulnerable.If 1.b4 it has nowhere to go.But black can exchange the other B first by 1…. Bxg2 2.Kxg2 Now by 2…. kb7+ he vaccates e7 for the B.Alternative 1.bxg7 Qxg7 clears e7 for the B. So,
1.Be4+ Now 1… Bxe4 2.Qxe4+ any 3.b4 traps the B.
1…. Kg8
2.b4 black has to lose a piece.
Very subtle, since the black queen being overextended is what makes it finally work after 1. Be4+ Kg8 2. b4 Bxb4 3. Bxb7
1.Be4+ Kg8 (…Bxe4 2.Qxe4+ Kg8 3.b4 traps the remaining BB and …g6 loses the h pawn to Bc1) 2.b4 Bxb4 3.Bxb7 and the BQ is overloaded.
I mean the BQ is overworked.