Find the decisive blow (difficulty 1035)

12345678 hgfedcba

Black to move

Show solution
12345678 hgfedcba
  1. c1–f1 key move
  2. g1–f1
  3. c8–c1

What makes it

The win is mate in two, paid for with a queen given up. It is the queen that strikes first. At 1035, a solid test.