Enemies start to orbit the torture rack if you expand it horizontally.

Started off with a 7x3 pillar-shaped torture room (the part on the right) and added an enemy unit to the bottom. While it was in use, I expanded it to the top right by 3 more racks in a line making an inverted L. This caused the enemy unit I was converting to start spinning around the rack in a wide circle as if they were flying.