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1st HM., Probleemblad, 2009

#3
LEO d1:
PAOs c2, e8:
VAOs d2, d3

1.PAc1! (2.PAd8+ Kxe4 3.LEc2#)

1...Sxf5 2.VAb4+ Kxe4 3.VAe7#
1...Rxf5 2.VAc3+ Kxe4 3.VAe5#
1...Bxf5 2.VAc4+ Kxe4 3.VAe6#
1...Kxe4 2.LEc2+ Kd4  3.PAd8#

The key PA makes way for the LE to mate. Black has three defences that capture on f5 intending to interpose along the threatened mate line from e8. Each of these is an anticipatory self-block, so White checks with the d1-d4 battery, in each case using the appropriate VA that will be able to be a hurdle on Black's planned interposition square. The flight defence reverses White’s second and third moves from the threat.