Obnoxious. The wheels on the Cacton are actually the front landing gear from a spaceship model I made once. And the cactus from Eddie Galaxy! The magic of reusable art! To fight Cactons, you have to start sprinting after them the second they fire. Usually you can kill them before they roll off to a new spot. If they do start rolling away, hide! Otherwise you'll have a faceful of needles before you have another chance to hit them.