Mate in 2

A nice crosschecker. The highly thematic key opens the black check line, sets up a battery, and prepares the pin-mate after 1...Rxd4+.

1.Rb4! Thr. 2.Qe3#

1...Rxe5+   2.Se6# 
1...Rc5+    2.Sc4# 
1...Rxd4+   2.Sb3# 
1...Kg5     2.S2f3# 
1...Rh4,Rg3 2.Q(x)g3# 
1...Rg5     2.Se2#