White sacrifices a piece, but has now both of Black’s GIPF-pieces at his mercy. The pieces on the b6-i2 line must be removed, so that Black has little left to defend Gc3 and Gd6. Even 1. … c2 isn’t a solution, because White has a threat on the a4-h1 line, too. That would give: 2. c1-e3;xGd6 / c1-c4 / 3. g1-g3;xGc4 / X.
So, depending on what Black decides to do, White shall choose between 2. f8-f5;xGc3 and c1-e3;xGd6 and will always be sure to capture Black’s last GIPF one move later.