Mandrake isn't magically changing sizes here. There's some forced perspective going on as she moves closer to and farther away from the "camera". :)
My rule of thumb with Mandrake's "picture speech" is to express the meaning, not the spelling. A thumbs up meaning yes. A sun meaning hello. A smiley face meaning happy. However, some words are incredibly hard to translate into images that can be quickly and easily understood by everyone. 'Well' and 'I dunno know' are a case in point. Thus, for this one time, in panel 2, I expressed the spelling of a word and not the meaning of the word. I hope you all can forgive me.
On another note, this is the last comic of 2011! We'll be continuing the story next year, of course.
With that in mind, I ask the readers an important question: What do you want from Mysteries of the Arcana next year? Something related to the story? A trade edition? A new website? Bonus features? Let us know what would help keep you here. The turmoil of artistic changes this year lost us quite a few readers. I don't intend to pander, of course, but I do need to start growing this comic again.