As I understand it, a big thing in 3.5E D&D that was spread around a handful of splatbooks, official and third-party both, was something like customizable metamagic. Which was something that allowed for horrendously broken magic workings, and which has had even the smallest hints of similar flexibility nerfed into the ground in all later D&D systems, and offerings.
I... think I would have heard of that. Metamagic grants some flexibility, but it's hardly customizable. Most of the time it's not even worth the cost of the spell slot. Let alone the feats you have to burn just to use metamagic at all.
Wow, and here I thought I couldn't hate the newer editions of D&D any more.
See, now, this is where you get the right to complain.
I only have secondhand knowledge of the subject, honestly, but this is a webpage that is at the least an interesting starting point of all the things that 3E and 3.5E could do.
One thing of note is that the worst game-breaking stuff is often, though not nearly always, available at later character levels. Something that 4E and later D&D has focused on is more minimizing many of the old paths to such overpowered abilities even later on, but they instead focus on giving a lot of possible options that ideally aren't broken as early as possible.
