If you use the snake-men in the rules as a model, they gain 1 HD for every level beyond first. A 1st level snake-man necromancer has the standard 2+2 HD, while a 10th level one has 11+2. I suppose other monsters with classes would work the same way. So a 1st level scorpioid witch would have 5 HD and a 5th level one would have 9. I personally would give a monster with a class all the benefits of their class at level (FA, CA, special abilities, etc.) and I would use their class level in place of any other metric. Anyway, monsters with classes still use the monster attack table, right? If so, the HD FA will always be the same as, or better than, the class FA.
EDIT: What Jeff said.
Last edited by Blackadder23 (5/24/2014 9:41 am)