Connecting the rooks on the b-file with the forcing 1.Bxd6 should win the bishop on h8 and the game. Black is forced to move the rook from f8, and white will just play Rb8 with check or with check after a pair of rooks are exchanged on b8- black just doesn't have the time to get the bishop to safety. Probably the best black can do here is:

1.Bxd6 R8f4 2.Rb8+ Kf7 3.Rxh8 and white will have the threats of Rxh7 and queening the h-pawn.