Neverwinter Nights classes
I've never messed around with Kaedrin's Prestige Class Pack before, but I'm in the process of installing it now because it'll let me put together the build I want for my next OC/MOTB run. (For the curious, I want to use the Stormsinger PrC to have a 30 Warlock for Eldritch Blast purposes and a 14 Bard for song purposes, with some other goodies besides).
It's easy to go through the feat, class, and spell lists and find all the new stuff - and there's tons of it, but I haven't been able to find a good list of existing feats, mechanics, and other things that Kaedrin's changes or replaces rather than simply adds. Some of these are fairly easy to spot over at NWN2DB once you've been told to look for them. For example, Expert Tactician was changed from a base version which was bugged and didn't actually do anything, to a flat +1 BAB feat. However, not all changes are even documented to that degree; I've seen references that Kaedrin's nerfs Combat Expertise by making the to hit penalty apply to touch attacks, but I can't find documentation of this anywhere.