1.Qh3 threat 2.Bc6+ Kxe5 3.Re4
1...Rxe5 2.Rd4+ Kxd4 3.Qd3
1...fxe5 2.Qd3+ Ke6 3.Rxd6
1...Sxe5 2.Rxd6+ Kxd6 3.Rd4
1...Kxe5 2.Qe3+ Kf5 3.g4; 2...Kd5 3.Rc5 or 3.Rd4
1...f5 2.Qd3+ K any 3.Qxd6
The three selfblocks on e5 result in an AB-BC-CA cycle of continuations and mates. If e5 was simply unavailable to the black king all three sequences would work, hence the selfblocks are Stocchi blocks, the dual avoidance working because each defence has a harmful effect on one of the thematic white moves (direct guard of d4 or d3 or vacation of e7). The unimportant dual after the flight is taken could be eliminated, but the composers clearly felt it was not worth spoiling the excellent economy by adding the necessary extra material.
Jacob Hoover: The white responses to three of the captures display an interesting cyclic pattern. But wait, there’s more. If Black were to replace the e5-knight with a dummy piece, all three of these continuations are possible! This means we have Stocchi blocks. A fourth capture, 1...Kxe5, results in a continuation leading to an unfortunate dual. However, the rich cyclic content more than makes up for this. The fifth defence is yet another selfblock.