"I don't know what magic system you're working with, but it can thwart mine in at least some contests," says Stella, "and mine would do a much better job of that goal. It does, on Mars. People cannot make significant trouble for each other on my Mars. Is it just - clumsy? Not very smart? So you have to rely on judges and cliffs and the like, you can't just ban troublemaking and have done?"