 Through its incessant prowling throughout the Land of Oz, however, the Glass Cat has acquired intimate knowledge of its complex terrain; and it is generally willing to exploit this knowledge to the benefit of Dorothy and her friends.In "The Magic of Oz," for example, the Glass Cat guides the rescue party that saves Trot and Cap'n Bill from entrapment on the Magic Isle.And the Cat is virtually invulnerable to harm, which is a great advantage in its various adventures.