[tomc]

For us, the GM would always rule on illusions on a case by case basis, to the frustration of some of the players. Of course, this meant out world was not consistent. At least, not in a way apparent to the players. They eventually got comfortable with the idea that there weren't many hard and fast rules in the world.

If you let them, illusions become the generic universal creation spell. Now that could be fun in a world where illusions can do just about anything, and lots of non-wizards also know it as their only spell. But it wouldn't feel like traditional TFT.