Yes something like that. Plus, if I remember correctly, Nick said he'll train
the twins in the elemental magics not teach them. You can't train someone in something they don't know, not even the basics. They just had to learn how to tap into that power..
Moreover, in the Alchemyst it says that Dee had mastered
the art of Necromancy. I believe he, like every awakened Humani, had the magical potential for it and through years of practice he mastered that specific art/type of magic.
and I wasted my vote on Germain!
Sooo wrong. We all thought that The Necromancer was Germain.. I bet you laughed a lot, didn't you Mr. Scott??