Special thanks to Dumb-Age Master for inspiring me to look over this class with his answer in the Simple Question thread.
Man, this class is awesome. It's right before the Shadowcraft Mage, so it looks weak by comparison, but the potencial here is incredible. Races of Stone, by the way. Here's a couple big abilities:
1) You can cast Arcane spells with no problems in heavy armor. Nifty. This way, you don't look like a caster.
2) You can make runes, much like scrolls, for free, with the Share Runes ability. This means during downtime days you can create tons of such runes, and anyone in the party can later use them. You can do this (Con Modifier) times per day, and note that you must be a dwarf to enter the class. This ability is seriously incredible. Just imagine a few uses:
a) Create runes of Animate Dead, give them to everyone in the party. Now the whole party has hordes of minions.
b) Give personal only Wizard/Sorc buffs to the melees for later use. Some of those are really nice.
c) Give the Rogue a bunch of runes of Shrink Item and Explosive Runes, and watch pure chaos ensue.
3) You get the ability to cast any spell you know (lower than your max level) as a spell like ability, permanently, at the cost of a higher level spell slot, 20 times the gold cost of the spell, and the exact exp cost of one casting of the spell. Now you can cast it twice per day. Why hello thar, Animate Dread Warrior. Mineralize Warrior can come too. And I wonder if we can get True Creation on our class list?
There is the annoyance that you need arcane casting and full plate proficiency to enter, making it difficult to get into. Also, you have to be a dwarf. The simplest entry would be Fighter 1/Wizard 4/Runesmith 5, but I think I'd prefer Crusader on the entry if xp penalties weren't an issue.
JaronK