If you could trade places (and powers) with any fictional spellcaster, who would you choose and why?

Geek Question of the Day: From books and movies to shows and comics, there are countless spellcasters out there, so today we're asking; If you could trade places (and powers) with any fictional spellcaster, who would you choose and why? Obviously any source is up for grabs, including ones of your own creation, so go for it! Oh and yet another shout out for Julia Piatt, who suggested this to us!

Image source: http://bit.ly/2ZR6lpr