Probably not what you are looking for but Guilder (a 7drl) has an amazing magic system. You have magic words that you can string together to create your own spells. An example: one kay thaum prae (true name) yal aes surutai two em jiha ptoron uum! (take one thousand of my or anothers mana and turn it into heat two spaces in front of me [end spell]). If you want to try it I suggest writing all the key words down. I haven't figured out how to actually get rid of the heat, or a faster way to cast then typing all of that, but it has lot of potential if polished up.
A word of warning though, its not really a game yet, and horribly unbalanced. You can draw essentially unlimited mana once you figure out how to and.. I don't need to explain why that breaks balance. Also the level gen fails to create doorways to the rest of the level (and stairs) sometimes.
I could write up some interesting ideas to make this work in a more traditional RL, but if I ever get around to making a roguelike I'm going to be focusing more on off-genre fantasy than wizardry.