Endgame: "Draw, Lose, or Lose"
Black to move:

Black has just promoted his pawn as bait to lure White's King to h1. Black has a chance to draw if he makes the right move; all others lose.
Spoiler alert below:
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1. ... Kc3 is the right answer. White will delay sac'ing his Bishop until the pawn reaches d2 but then won't have time to both capture Black's f pawn and defend his own.

The two other King moves allow White enough time to recover.
The reason I played Bb6 was that it prevents ... Ke2, attacking the pawn, due to Bxd4, defending the pawn.
As usual, I miscalculated, thinking I had a won endgame. But it wasn't until Black's 50th move [he played 50. ... Ke4 and now cannot reach a square to support the pawn advance, which means White does not have to sac his Bishop] that I was able to take over, thus showing again how tricky even the simplest of endgames can appear.