1.b8=R!
Kc7 2.Re8 Kd6 3.Kc4 Kc6 4.Re6+ Kb7 5.Kb5 Ka7 6.Re7+ Kb8,Ka8 7.Kb6 Ka8,Kb8,Kc8 8.Re8#
5…Kc7 6.Ka6 Kd8,Kc8 7.Kb6 Kc8,Kb8,Kd8 8.Re8# (Author)