Very few times you'll want to seven dice something. I guess for lulz, you could take 'Cupped Hands' as well, and then seven dice 'Purple Sun' or large-version 'Pit of Shades'.
On the other hand, having that free dice pretty much doubles your casting output. So yeah, try to maximise your output, to burn out scrolls and other one-use magic defense early. Burning out dispel dice is also good, as they will always have less.