In the book, not the movie, she did not have green skin, and she had only one eye, not two or more with any non-functional. The one eye was, indeed, telescopic in nature, so she could see all of her realm in the West. When Dorothy and her friends set off to destroy her, she saw them coming from a long way off. There was no sneaking into the castle at all. She had a reputation for making slaves of those she captured. She had no idea who Dorothy was, but sent four waves of minions to dispatch them all, except for the Lion, as she thought it would be amusing to hitch him up to a cart. Dorothy escaped murder by the apparently visible mark of the Good Witch of the North's kiss on her forehead. By the way, the witch of the North remained nameless, the Good Witch of the South was named Glinda, and she did not appear until the end of the story, when Dorothy sought her out to go home.