Ahhh... runes, so many people want to make them all powerful gimmicks. We have used runes in all my games, and used them alot in C&S. I would consider some of them as skill. Or alternate as quick spellls. I would look at a copy of Authentic Thaumaurgy by Bonewits. For ideas. Also, in the links there is a great site, Vikings and Skraelings, he does extensive work in runes. Also there all sorts of "runes". There is a great book, magical alphabets by nigel pennick, it is available thru amazon. The work for you is manyfold though, for us the runeworker has to know his runes and as he gains in knowledge he can do more works. And there is one more thing, your player has a permanent runestone, how does he feed it? Is there a salamander, or djinn or other fire elemental enclosed within. Things could get messy. I will try to pull my notes together, and give you some ideas, if you need them. If you are using regular runes, I would suggest figuring their meaning in your world. Each is a separate lore, and then there isa general runelore to get them to interact with each other. Could get messy!!!