Barks' commentaries:

The tricky world of villainy is peopled with many sorts of rapscallions: Burglars, bamboozlers, sneak thieves, legal loophole law-twisters, dynamiters, and organized gangs like the terrible Beagle Boys. But topping all of these types in sheer cussedness are witches!
One dreadful day in 1961 the slithery, slinky Magica de Spell entered Uncle Scrooge's office and announced that she was a sorceress (WDCS258 Ten Cent Valentine (and it was in 1962) - Editor's remarks). Uncle Scrooge thought that was very funny, and he laughed and laughed. He hasn't laughed since; he has been too busy saving his fortune and his deified old Number One Dime from the supernatural clutches of that sure-enough, honest-to-god, unspurious, professional hex-throwing sorceress. In 1964 he barely saved his face in this fantastic battle which shows witchcraft at its perfidious, spell-casting worst.

Magica de Spell is outright fantasy - old-time sorcery jazzed up with a little bit of humor. She was another menace that I developed because I couldn't be using the Beagle Boys all the time. So I thought, why not invent a witch? If I made her look kind of glamorous, with long sleek, black hair and slanty eyes, she could be an attractive witch. Magica herself was modeled on the dark-haired witch from the Charles Addams family cartoons in The New Yorker, which I liked very much. And that seemed to pay off all right in Italy because they just went nuts over her; over there she was one of the most popular characters. In fact, she lived on Mount Vesuvius.

When she first came to see Scrooge, she had a gimmick she was working on. She was trying to get a dime from each of the rich men in the world. She thought if she got a coin from each one and melted them all into one amulet, that would make her just as rich and lucky as these millionaires. So when Magica asked Scrooge for a dime he thought it was kind of amusing. But the one he accidentally gave her was the old Number One Dime. All hell broke loose. Aided by the nephews, Uncle Scrooge took off after her. She escaped to Vesuvius with the old Number One Dime. Uncle Scrooge and the ducks had to follow her all the way to the volcano, where she was going to melt it, in order to save the dime.
And from then on Magica has been after that Number One Dime. That's the only object she wants more than anything else. She knows that if she took a barrel of Scrooge's money, why, in a little while it would be gone, but if she had that old Number One Dime and made it into this very lucky amulet, she would have many barrels of her own money and would be the most powerful person in the world. She'd also be the richest.

This story features just another of her many gimmicks for trying to get that dime. It's a story that uses a lot of her sorcery and her props, like her black raven and the fact that in the end she's gotten into the land of the faceless creatures, and she's become faceless herself as a result of the kids' smartness. She can't think of anything simple for removing her magical gook from her face. She tries all kinds of potions she's put together, and the kids meanwhile have looked in their Junior Woodchucks' Guide Book and found that soap and water would take it off. It shows that sorcery is a superficial kind of thing in that respect.
I don't actually know how I got the idea of the formula that would transfer faces. Those kind of things just pop up into my head. Like thinking up crazy names, they just come falling out of the sky...