I have taught this game to at least 10 different people since getting it at Gen Con. Learning to teach it is an evolving process, as is learning to play it.
There is no question as the owner and the experienced player, you have an advantage. Furthermore, since you have built your opponent's spell book, you have another advantage.
To mitigate these circumstances, and after some experimentation with teaching, it is now my standard practice to allow my opponent at least fifteen minutes, or longer if they need, to pore over their spell book after I've explained the basic ruleset to them. I also offer to let them look over my spell book if they would like to.
At that point, as they have quite a few questions about card abilities and traits, I provide them with the codex and tell them to just look up terms they don't understand before asking me during play. That way, they are giving me less information about their plans. If they have questions during Planning that cannot be answered by the codex, I ask them to please wait until I have selected my cards, so that my selection is not influenced.
Finally, I try to not let my opponent do anything too unwise. I don't want to play their game for them, but new players inevitably do something they will really regret.
This seems to have worked well so far. Virtually everyone I have taught seems very interested by the game.
As an aside, there is no need to use proxies. All the cards you need to build two of the stater spell books at at a time are in the box.
I keep two modified books together, and then the other two mages I store as a deck with notes about cards I had to "borrow" from them so I can quickly rebuild them if someone wants to play those mges instaed of the ones already in the books.
Hope this helps.
