Find the decisive blow (difficulty 1420)

87654321 abcdefgh

White to move

Show solution
87654321 abcdefgh
  1. f6–e7 key move
  2. c7–e7
  3. b1–c1
  4. f7–f5
  5. g3–f5
  6. c8–f5
  7. d4–f5
  8. e7–f6

What makes it

A 2-point investment — the forcing line does the rest. It is the bishop that strikes first. It calculates 8 plies deep.