a) diagram

1.Sc6-d4 Rc7-c2  
2.Rf4-e4 Sd5-b4 #

b) wBh6-->a7 

1.Sc6-e5 Rc7-c3 +  
2.Kd3-e4 Sd5-f6 #

c) bSc6-->c5 

1.Rf4-d4  Bh6-c1  
2.Sc5-e4 Sd5-f4 #

Duel fields for entering one white piece and three different black pieces
3 different second black moves are made on the same square.
Second white moves are made with the one piece on the three different squares.(Author)