This has been posted on this board before. It is about the only way for a non-wild mage to get NRD without cheating. You still won't have the wild mage's 5% chance of a magic surge or its variable spell casting level - also, I doubt you'll be able to find the Chaos Shield spells anywhere.
If you cast the spell during play, you might consider saving first. I tried out a similar character in the starting dungeon and polymorphed myself into a squirrel the first time I cast the spell! What I find funny is that the squirrel then proceeded to kick some goblin butt
