Hali the witch must guide humans through magic world disguised as computer simulation

What if modern tourism and marketing collided with a fantasy world? You might get something like this, where the witch of the title gets a wombat familiar because surverys show visitors like wombats That's just the first of the strangeness of this book. (The familiar, a former sneak-thief, is charmingly cowardly as well.) Amusing. ( )