I wrote up an assassin for use in a River Nations campaign. She and other like her will be available soon from Jon Brazer Enterprises. Check her at now.
Very cool! NPC's are at least as useful as monsters. They are certainly harder for a novice DM to find ready made. The back story is fun, she sounds like some PC's I have known for a short time.
Ooh, nice to see a non-standard class used for an assassin character. Especially a magus, they don't seem to get used very often in official material (which I find odd, given just how good a class they are). Thanks so much for sharing this one!