Board Thread:Questions and Answers/@comment-5984859-20150717140732/@comment-25374175-20150731191108

Possibly, Clouse may have remembered all the spells in his free time as the Book of Spells has been passed to Garmadon, Clouse, and Lloyd.

And your right; their is not proof that there isn’t an Elemental Master of Magic, but unlike Amber, there isn’t an object that relates to Amber (Magic being the Book of Spells) and their is a confirmatation of an original Elemental Master of Amber.