Q 181: In 3.0 Abishais (which have regeneration) took normal damage from "holy water, holy weapons, and blessed weapons." In 3.5 they take normal damage from "good-aligned weapons, and from spells or effects with the good descriptor."
Bless Water
Transmutation [Good]
Level: Clr 1, Pal 1
...
This transmutation imbues a flask (1 pint) of water with positive energy, turning it into holy water.
Should holy water still deal normal damage to an Abishai? Holy water is created by a spell with the [good] descriptor, but holy water itself doesn't explicitly have the good descriptor.
I can see it ruled either way, but I'd go with yes, holy water does work. Partly because the old version was harmed by it, partly because the damage is still (technically) part of the effect of a good aligned spell.
Lo and behold, I remembered that there acually ARE abishai in the Red Hand of Doom. Blue ones are present in the Fane of Tiamat (the last part of the adventure).
Interestingly enough, they note that holy water and good weapons deal normal damage to Abishai (but not spells of the good descriptor...) This one also still has DR equal to its hit dice (that's what the 3.0 versions did, but FC2 lowered it and made it not advance if they advanced in HD). So we have 3.5 stats for the blue abishai that conflicts with the 3.5 stats in FC2. So... DM's choice!
*Really, I know that FC2 supersedes RHoD (Dec 2006 vs Feb 2006 printing), but really, I'm just gonna use what I want, or a mix of the two

I'll probably give it the regeneration based on HD (ie - Regen 8 for a red) but allow good weapons, holy water, and spells of the good descriptor to deal normal damage to it. But I'll keep the FC2 SLA's that they are given (loses animate dead, desecrate, and major image, but gains Wrack, which will be more useful

).
Now to drop some holy water in the lap of my PC's somewhere along the line...
Re: Shadow Creature - I just realized that the location where the PC's will find this thing corresponds to the Svalbard islands (roughly 300 miles north of northern Norway), which will be in polar night by the time they go check the place out...
Man, I'm an evil DM, even when I'm not trying to be.