This guide is well done and very helpful, I would increase the approximate time for completion to 4-5 hours though. Even on the easiest difficulty, the enemies have a decent amount of health and you can't resort to 1-shot magic because then you wouldn't get the Pteryx achievement. Otherwise, the guide is pretty much perfect.
Also, the Kobolds weren't attacking me either at the missable achievement, they were just supporting the boss with buffs.
Completed Retail: 30
Completed Arcade: 11
50,000 - 9/13/11
"Cocaine's a hell of a drug" - Rick James