Just a thought but if we need to have a "full deck" and we can repeatedly cast spells then we should probably only have access to about 8-15 different spells to account for the idea of playsets.... Otherwise a player could potentially have 40 different spells available at nearly any time as we have no "hand" to worry about.... Which bring me to my next point. How do spells like Thoughtseize, Duress, Thought Scour, Brainstorm, Ancestral Visions, Demonic Tutor and the such?