Helpmate in 3
b) Black pawn f2

a) 1.Se4 Sg5 2.S×f2 Se4 3.Sh3 Sf6. The knights exchange places, a common idea in helpmates known as platzwechsel. But what happens when a black pawn prevents the knight from reaching h3?
b) 1.Sg8 Sg1 2.f×g1S h×g8S 3.Sh3 Sf6. Both knights sacrifice themselves to allow pawns to underpromote and reach the same mate. This idea, where a piece is captured and a pawn then promotes to the same type of piece is known as the phoenix theme.

Jacob Hoover: Yes, rather quirky indeed, and, as far as I’m concerned, highly amusing.