Every chessplayer will remember being dismissive first than delighted at Reti’s famous 1921 composition. White to play and draw looks like an impossible task, because the black pawn is out of reach, while the c6-pawn can be captured.
The triangulation scheme recurs in the second position, which I came across as a tactics puzzle (composition by Ernst Frederick Holm, Deutsche Schachzeitung, Jan. 1913).
If Black plays …Bh3-g2, it’s a draw. First White obstructs the bishop.