Next week I'll begin the first session of my PC's entering the Expedition to Castle Ravenloft adventure. The thing is, my group of 3 PC's are 9th/10th level, so I need to advance at least the "main" bad guys by about 3 levels.
I'm looking through the encounters, and one of them has the PC's against a group of werewolves and an insane Nymph (she has the tainted raver template from Heroes of Horror). To help you frame this in your mind, recall that Nymphs are a 6 HD fey with the casting ability of a 7th level druid, and they can blind humanoids as a free action (and stun at will).
Due to the Tainted Raver template, Valicia the nymph only has a Wisdom of 11 (restricting her to 1st level spells), but a Charisma of 25. She can also add her Cha mod to Will saves in place of her Wis mod (meaning she gets 2x Cha to will saves - she has a Will save of +18). Also, her write-up includes the fact she has both Moderate Corruption and Depravity, but neglects the fact that due to that taint she gains 2 bonus feats (per Heroes of Horror, page 67). However, that entry only says "taint," not corruption or depravity. It's my understanding that each is tracked separately, and thus each grants its own bonus feat, correct?
Ok, so here are my thoughts for advancing her (despite the nymph entry in the MM saying they advance by HD). I'm going to advance her with 3 levels of Druid, granting her 3 more casting levels (for a total of 10), an animal companion, woodland stride, and trackless step. Her HD levels also grant her an ability bonus (going to Wisdom, allowing 2nd level spells unaided) and a bonus feat (in addition to the 2 bonus ones she gets from her taint).
I'm going to give her the Natural Bond feat, allowing her to have a boosted wolf animal companion, as though she were 6th level. I'll probably also give her Craft Wondrous Item, thus explaining the +2 Periapt of Wisdom I'll give her, which will then allow her to cast 4th level spells. Lastly, I'll give her some sort of metamagic feat, allowing her to get extra use out of the 5th level spell slots she'll have, but can't put 5th level spells into (due to her Wisdom score). What metamagic feat would you suggest?
Lastly, is there some means, via a feat or PrC class that can change druidic casting to Charisma, rather than Wisdom? I can't think of one, but have a nagging vague remembrance of something to that end.