"It looks as if you need only enter the field for long enough to recognise the bannus and take hold of it. Then you order it to stop."
"Fight my way through a mob of dancing girls and snatch the dulcimer off the leading damsel," Reigner Two said morbidly. "I can just see myself. I think the fools who invented this thing might have thought of a simpler way to stop it. What's wrong with a red switch?"
Diana Wynne Jones