To shoot through a one-cell gap, mirror the enemy through it (the French call it symétrie). A routine that works in every fight: ① find the anchor, the gap. ② Count from the anchor to the enemy: 2 cells through and 1 to the side. ③ Count the same the other way: 2 before the gap and 1 to the other side. That is your cell, and the line passes exactly through the centre of the gap.