Adding spellcasting levels to high CR monsters

[johnsemlak]

I've touched on this topic before, but again, I want to add some spellcasting powers to a high CR mosnster who has some spell like abilities but no spellcasting levels.

THis time, it's the Storm GIant

I'd like to add a few levels and somehow significantly increase its' powers. Adding levels of either Paladin or Cleric are sort of what I'm after. But in order to give the Storm Giant powers that are at all useful at his CR, I'd have to add 10+ levels., which I"d prefer to not to.

Any useful tips?

Perhaps what I need is a 'Giant' prestige class, which only giants can qualifiy for, and which give high-level powers right away. Are there any such PrCs?

 

[the Jester]

Keep in mind that a nonassociated class adds 1/2 CR per level to a monster, at least 'til the base creature has as many HD from the class as from its race. So 10 wizard or sorcerer levels only increases your giant's CR by 5.

 

[Conaill]

Keep in mind that a nonassociated class adds 1/2 CR per level to a monster, at least 'til the base creature has as many HD from the class as from its race.

Yup, and I would houserule that you add 1/2 CR per class level up to the CR of the monster, not the HD. Because there are a few monsters (especially some of the young dragons) with a CR that's less than half their HD.

For example, a Young white dragon (YWD) is CR 4, 9 HD. Let's say Rogue is a nonassociated class. According to the official rule, a YWD Rog8 would only be a CR 8... same as a regular Rog8! With my houserule, a YWD Rog4 would be a CR 6, but a YWD Rog8 would be a CR 10. That seems more sensible...