Find the decisive blow (difficulty 1485)

12345678 hgfedcba

Black to move

Show solution
12345678 hgfedcba
  1. a6–e2 key move
  2. d1–b1
  3. e2–f3

What makes it

It starts with a queen move and forces mate in nine. A fork: two or three pieces fall under attack together. 17 half-moves of forced play.