A minor piece problem and a pretty example of its theme.
Clearly the a8 bishop must mate, but Black’s threat of capturing the d2 pawn must he dealt with. 1.Bb7? fails to 1...Sc7!, The solution is a decoy followed by blocking in the black bishop to set up a zugzwang. 1.Bd8 Bxd8 2.Bb7 (threat 3.Ba6) Sc7 3.Bc8 (threat 4.Bf5) Se7 4.Bd7 followed by mate on b5 or f5 (1...Sc7 2.Bxc7 etc.). Such an incarceration is known as the Seeberger theme.
Juha Neitola: With all possible mating squares easily guarded by the black knights and the d2 pawn vulnerable, White clearly needs a miracle. And as it happens, there is a black hole for both dark squared bishops at d8! We will have a nice symmetrical Seeberger position after White’s fourth move if he is smart enough to advance with the shortest possible bishop moves to avoid the zugzwang himself.