It's funny that I really don't have a whole lot of spell cards, I guess that is by design. Of the cards I listed, the most I have is 11 Magic Bolts. Weird, since you start off with a magic bolt, and after 400 plus battles I only have 11 of those.
Second is a 3-way tie, of Fly, Life Stream and Spartoi. I have 10 of each, and in a 4-way tie for third I have 9 cards each of Thorn Fetter, Shatter, Holy Word 6 and Dream Terrain.